VID’S GUIDE: Upgrading/Rebuilding Flippers

VID’S GUIDE: Upgrading/Rebuilding Flippers
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VID’S GUIDE: Upgrading/Rebuilding Flippers
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VID’S GUIDE: Upgrading/Rebuilding Flippers
Published on
November 7, 2020
Updated on
November 7, 2020
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Written by Vadeem/Vid1900

“Most flippers on old games suck. Only the cool kids rebuild them for top performance.” – Vid1900

Just got back from a collector’s house and 75% of his flippers were weak. Games looked good and clean, but he had no idea how to set up his flippers. There were a lot of terrible flippers at the Michigan Pinball Expo a few months ago, too. Finally, NJGecko wanted to know how to upgrade his System 11 flippers to the newer springs of the Fliptronic era.

Some of this is going to be old hat to the more experienced collectors, but clearly there are a lot of people who need a crash course in the basics.

First, what is going to be wrong with your flippers? If you never rebuilt them, probably everything!

The plunger will be worn, mushroomed at the tip, and have a lot of play in the links.

Your return spring will be limp (or if it is a Sys 11, probably broken).

Your EOS (End Of Stroke) switch will be pitted and corroded.

Your Coil Stop will be concave, causing the plunger to become mushroomed.

Your Coil Sleeve will be cracked or worn.

Your coils might well be the incorrect ones.

The Coil Plunger needs to be smooth so it does not drag in the Coil Sleeve.

A common problem is that the tip will mushroom and bind in the sleeve. This will create drag or seize the flipper entirely.

Another problem is that if the Coil Bracket ever became loose, or a plunger spring ever broke, it can chew up the Plunger. This of course leads to the Coil Sleeve becoming chewed up.

The EOS Switch needs to make solid electrical contact, or the flipper will be very weak.

If the contacts are all pitted and corroded, you can’t get good contact.

If the gap between the contacts is not correct, you will have weak flippers (more on this latter).

The Coil Stop takes a constant beating. As the plunger hammers away, it becomes concave and helps shape the plunger into the dreaded mushroom shape.

So, how do we fix all these common problems? We throw all that junk away and get a rebuild kit.

I know, there are people who file the mushroomed tips, clean dirty sleeves and re-stretch springs, but the flippers are the most important part of the whole game. You spent thousands of dollars on your game and now you are going to try and save $20 on a kit??? Your game deserves to play at factory (or better) condition.

You can get a kit from Pinball Life, or any other mail order place. Don’t expect to get a genuine Bally/Williams kit in the little plastic box. Nowadays, the patents have run out, so you get an overseas made kit.

If you have a System 11 game, get the newer (Williams reference #A-13524-8) kit anyway. It will have the much desired stronger return spring, and only requires a small (one time) modification to install it. Also get a pair of high voltage EOS switches (Williams reference #03-7811) as the ones included in the kit are for low voltage games:

Before you order, check page 2 of your owner’s manual and make sure that the correct flipper coils required for your game are installed. 50% chance if your game was once on route, at least one of them will be wrong. Sometimes the wrong coils were installed at the factory (like many F-14 Tomcats), so you really need to check this.

Finally, you need to order some flipper bushings. These are very important if you want to keep the flippers from cutting into your playfield, or creating unnecessary airballs. They don’t come in the rebuild kits, but you absolutely need them for a rebuild.

Start by labeling the wires that go to the flippers, you can use Blue Painter’s Tape. Then label the coils themselves. You can write on the coil plastic with a Sharpie (it cleans off with alcohol). Now you can put the game back together again without blowing anything up.

Unsolder your now clearly marked wires with a 25w soldering iron. If you don’t have one yet, your going to need one constantly to maintain a pinball game. Don’t buy one for less than $20, trust me on this.

If there are any “lane change” switches and wires ganged up with the EOS switch, label and unsolder those too. Unlike the EOS Switches, the Lane Change switches usually do not need to be replaced, only cleaned. Just pull a crisp $100 bill through the held together contacts, until the bill pulls through cleanly. The first pull will be very black with carbon.

Loosen the flipper nut, and carefully pull the flipper bat out from the top of the playfield.

Next, get out a 1/4″ nut driver and remove the hex head screws from around the flipper bracket. Take the whole assembly out of the game and onto a well lit workbench covered with newspapers. If you don’t cover your workbench, you will soon be sorry as the whole bracket will be covered with black carbon and iron dust.

The dust comes from the metal on metal pounding between the Plunger and Coil Stop. Some more dust comes from the spark that occurs at the EOS Switch. It’s filthy.

Unsolder the EOS Switch Capacitor, and put it aside.

Take the old Coil Sleeve out and discard it. If the sleeve is tight, press evenly on the bench to get it out. If it is absolutely stuck, the coil may have overheated at some point. Replace the coil, they are only $10.

Discard the old Coil Stop, the Spring, the Plunger/Link assembly, the Bushing, and the EOS Switch. No reason to save them as spares, because once you play on a game with new flipper mechs, set up correctly, you will never even think of reusing that old junk.

Take the saved parts to the sink and scrub with Fantastic cleaner (or any other degreaser) and a toothbrush. Don’t get the coil label wet or it will fall off. Just use the damp toothbrush and clean the coil inside and out.

Don’t put the metal parts in a tumbler for too long or with high abrasives. The parts are zinc plated and the tumbler could remove this protective plating. When you see restored games where the hardware is completely covered with white corrosion, you know somebody tumbled off all the coatings. If you, or someone before you already did this, tumble again and spray with a light coating of clear Polyurethane.

System 11 owners update:

Unless someone really took care of your game before you, you have the awful, conical spring that rides around the outside of the plunger. This spring is usually weak, broken and corroded. It is simply a poor design choice as it chews up the Plunger Link and sometimes the Plunger itself.

No doubt you have noticed the “snap” of the newer Fliptronic games and now you can have their superior snappiness too.

You will need to drill a 1/16″ (1.5mm) hole in the Capacitor Bracket. Don’t drill through the Capacitor itself (you removed it in the last step, yes?).

Measure from the picture below. Use a punch to keep the drill bit from walking around. Once you drill the hole, file off any sharp edges on both the front and back.

System 11 owners update part 2:

You will note that your new “Fliptronic” arms have spring tabs on them. Never again will they suffer with conical springs.

Now it is time to reassemble.

Put the new Bushing in the flipper bracket. All three nuts on the topside have to be tight, or your playfield can become damaged.

Put the new Coil Sleeve in the coil. This is where it helps to have a bag of Sleeves, because sometimes one will fit where none of the others will. If none of them fit, the coil may have overheated and really (I know, you don’t want to spend another $10) should be replaced.

The Coil Sleeve protrudes from the Diode side of the coil. Don’t put it in backwards.

Make sure the coil gets installed the correct direction. The Diodes or even the Coil Tabs tend to break if you put them next to the Coil Stop.

This is the correct installation of the Coil; Diodes safely away from the Coil Stop. It matters, do it right.

Some Coils were installed backwards at the factory, so you may have to pull a little slack wire from the harnesses to reach the proper position. Don’t worry if you have to clip a few nylon Zip Ties to produce the slack you need.

If there is a little plastic nipple on the coil, you can cut it off, or cut a little notch in the coil bracket with a Rat Tail File or Dremel.

When installing the Coil, squeeze the brackets towards each other as you tighten the cap head bolts.

You don’t want the coil moving around robbing your game of power. Tight is what you want, no play, no slop.

It’s not in your kit, but remember to zip-tie your Capacitor to the bracket.

Now solder the Capacitor to the new EOS switch. The Capacitor has no polarity, that is a fancy way of saying that either lead can go to either terminal of the switch.

The Capacitor helps keep the switch from pitting as much. Yes, you should use it.

Now for the section that strikes fear into the newbies hearts = setting the EOS Switch gap!!!

When the flipper is not energized (in its relaxed state), the EOS Switch needs to have solid contact.

So gently bend the leafs of the switch so that they are nicely sprung together. Not just barely together, but actually making good contact.

Now when the flipper is energized (the plunger all the way into the coil), we need the EOS Switch to open or the coil will overheat.

Press the plunger down all the way till it stops with your finger, and make sure the switch gap opens to EXACTLY 1/8″ (3.2 mm). Not more, not less. (there are a few System11 games that want less than a 1/8″ gap, check your manual)

You may have to fiddle with the leafs to get them touching when relaxed and 1/8″ gap when plunged, but it is a lot easier to do on the bench than installed in the game. You will get the hang of it, take your time and get this exactly right.

A Leaf Adjuster tool makes setting switch gaps and tension a breeze. If you own a pinball game, you should have one in your tool box:

In your goody bag, you got a little Gap Tool (sometimes called a fork or by Williams official name “Flipper shaft end play spacing gauge”). Many people do not even know why they have it.

I’m not sure anyone sells them anymore, but the Williams part number was 03-8194.

I measured a few of them and they are consistently .7mm, so maybe someone wants to make a knockoff.

After you put the flipper mechs back on the playfield, you need to set the gap between the Flipper Bat and the top of the Flipper Bushing.

I’m showing the Gap Tool on the Flipper Bushing NOT installed in the playfield, just for clarity.

I can hear some of you moaning that you did not get a tool with your game. Lucky for us, most credit cards are about .7mm thick. Cut a notch in your card and make your own. Don’t cut through the magnetic strip or the embossed numbers, if you ever want to use the card again.

The original Williams instructions show the tool being used between the Crank and the Flipper Bushing. It is much easier to put the tool above the playfield, between the Flipper and the Bushing. That way the tool is far from the under playfield clutter. If it is your first time adjusting flippers, you can rubber-band the tool to the flipper so you don’t have to worry about it falling off.

If you want to change your old Series Coils out for new Parallel Coils, first label your wires.

The wire(s) that come from the Banded side of the Diode lug is your 50v = make sure you note this.

The center lug goes to your EOS Switch and the non banded side of the Diode lug has both the EOS Switch and the Power Return wires.

Same strength replacements:

FL24/600-30/2600 Series wound = FL11722 Parallel

FL23/600-30/2600 Series wound = FL11630 Parallel

Install your new parallel coil and sleeve. Remember that the lugs DO NOT go next to the coil stop.

The wire you labeled 50v power goes to the outside lug with the Banded Diode (the thick and thin coil wires).

The center lug (with the thick coil wire) goes to your EOS Switch.

The outside lug with the Unbanded Diode (the thin coil wire) goes to the EOS Switch and the power return wire.

The capacitor goes to both sides of the EOS Switch. The capacitor has no polarity, so either leg can go to either side of the switch.

QUESTION: Will this upgrade work for Data East machines as well? I saw it specify William and SS machines. I need to rebuild the flippers on my DE Batman and wanted to do the upgrade to it as well if it will work.

ANSWER: Yes, it’s basically the same thing.

Remember that Batman has early and latter versions of the flippers, so make sure you order the correct kit for your model.

QUESTION: Hey, Vid…should I replace the diodes during a flipper rebuild?

ANSWER: I never do unless they are cracked.


Ok, so you’ve got an old game like Disco Fever and you want to update to the modern style flipper mechs. This will REALLY tighten up the feel of the game and eliminate that ‘bounce back’ feel.

First label your wires so you know where your 28v and ground is.

Next pull out all the old mechs.

You might give these away to somebody who is a hard core collector – those guys want everything EXACTLY how it came from the factory.

Here for ourselves, we want the snappiest flipper action we can get.

The first problem is that the old coils are shorter than the modern standard, AND they are 28v instead of 50v.

So we need a SFL 19/400 – 30/750 coil. Often used in games like Black Knight*, the coil is full size, 28v and has plenty of power. Exactly what we need.

You also need a base plate, flipper bushing and a high voltage EOS switch (don’t reuse the old one that lacks the “helper” spring leaf).

Terry at PL will actually make the entire assembly for you for only $36:

Here are the options to choose:

I know right now many of you are saying “Thirty Six Dollars??? To rebuild my flipper?”, but look at it this way:

  1. You are getting a completely new everything. Nothing to polish or clean.
  2. You are getting that “snappy” Fliptronic feel – the best flipper design ever made.
  3. Rebuild kits in the future will only be $21 (instead of $54 for the old style Williams one).
  4. You can sell your old mechs and coil and get a few bucks back towards your new stuff.
  5. You can use modern flipper bats, so you get all the cool colors, transparent, illuminated……

* Firepower II, LaserCue and Starlight were the first games to switch to 50v flippers.

Find room on the playfield for your new mech.

You might have to spin it 180* to make it somehow fit between lights and wires.

Remember that you have a Right and Left mech, so don’t make the rookie mistake of putting them on the wrong side.

Note that the solder lugs for the coil are mounted AWAY from the Coil Stop.

Note where your 28v and GND wire goes in relation to the band on the Coil Diode.

Unless your flipper bats are something special like Time Warp or Disco Fever, just buy new, smooth shaft ones like modern games use:

But if you do have special flippers and need to reuse them, just make sure that the clamp is squarely on the shoulder. If it’s not, you won’t be able to get a good enough grip on the shaft.

Shave a small amount of Nylon off of the Flipper Bushing to give you the necessary clearance. Normally less than 1mm.

Gently tighten the shaft clamp, but do not crank down on it yet.

I normally set the EOS Gap while the flipper is still on the bench, as it is easier.

Note that when the flipper is at rest, the helper leaf spring is putting strong pressure on the short contact leaf.

You want to be sure that, as the gap is opened, you see that the helper spring is making the short contact leaf follow into the gap.

If you don’t do this, one flipper will be weaker than the other – often 10 minutes into the game.

Here you see the EOS Switch gap with the flipper fully extended.

Note that the gap is exactly 1/8″ (3.2mm). Not more, not less.

This makes for STRONG flipper action, by insuring that the flipper does not switch to low power until the very last millisecond.

Finally, align the flipper with the ball guide, so the ball has a perfectly straight path, or in the case of Curved flippers (Williams never called them “Bananas”) use the flipper Alignment Pin.

The Alignment Pin is the steel hole behind the flippers, often overlooked. Put a drill bit or fat toothpick in the hole and tighten the flippers clamps down while holding the flipper against it.

That’s it.

Your old SS game will play super tight with new mechs, and if you’ve never played Time Warp with tight, snappy Curved flippers – you are in for a treat!

Games made from 02/1992 to 04/1993 have longer flipper travel, thus use the A-12111 Coil Stop:

  • Getaway
  • Addams Family
  • Black Rose
  • Doctor Who
  • Fish Tales
  • Creature from the Black Lagoon
  • Whitewater
  • BS Dracula
  • Twilight Zone


Games made from 08/1993 to 10/1998 have shorter flipper travel, and thus use the A-12390 Coil Stop:

  • Indiana Jones
  • Judge Dredd
  • Star Trek: The Next Generation
  • Demolition Man
  • Popeye Saves the Earth
  • World Cup Soccer
  • The Flintstones
  • Corvette
  • Road Show
  • The Addams Family Gold
  • The Shadow
  • Dirty Harry
  • Theatre of Magic
  • No Fear
  • Indianapolis 500
  • Johnny Mnemonic
  • Who Dunnit
  • Jackbot
  • Congo
  • Attack from Mars
  • Safecracker
  • Tales of the Arabian Nights
  • Scared Stiff
  • Junkyard
  • NBA Fastbreak
  • Medieval Madness
  • Cirqus Voltaire
  • No Good Gofers
  • Champion Pub
  • Monster Bash
  • Cactus Canyon


The following games used the A-10821 coil stop:

  • Laser Cue
  • Space Shuttle (some machines, but not all)
  • Sorcerer
  • Comet
  • High Speed
  • Grand Lizard
  • Road Kings
  • Pinbot
  • Millionaire
  • F-14 Tomcat
  • Fire!
  • Fire! Champagne Edition
  • Big Guns
  • Space Station


OK, some of you guys were giving me shit for encouraging people to just install modern flipper mechs in older machines (

I still think this is a good idea, as the replacement parts are cheaper, the action is tighter, the return springs are snappier, and you can use any style/color flipper bat you choose……but I do respect someone who wants everything original.

This part of the guide covers the last EMs all the way through the early SS games.

So head on over to Pinball Resource with $46 in hand for a complete rebuild kit, and here we go:

The Williams EM/SS flipper mech is actually a pretty simple, durable assembly.

You have a Coil that drives the Plunger into the Coil Stop.

As the plunger reaches the Coil Stop, the EOS (End Of Stroke) Switch becomes open, switching the electricity in the coil from a High Power Winding to a Low Power Winding. This lets you keep the flipper in the up position to hold the ball, without the Coil overheating.

When you let go of the flipper button, the Coil de-energizes, and the Return Spring sends the Flipper back to the home position.

Here we can see some typical damage to the flipper mech.

The rubber insulation that engages the EOS Switch is worn all the way to down to the metal. (if we had no choice but to fix this, we could use a piece of shrink tubing).

The Spring is rusty and abrasive. When they get this corroded, they usually just break.

The Link is loose and sloppy. The holes have become enlarged so there is now much play in the system.

The plunger is unevenly worn, so this adds even more play. The tip of the plunger is “mushroomed” from repeatedly slamming into the Coil Stop. This makes the plunger drag in the Coil Sleeve, making the flipper weak.

I know someone is thinking they would just file off the mushroom end, and install a new link. These are the same guys that reuse oil filters in their cars. Don’t do it. Just buy new, tight parts!

Start by marking the flippers so you know which one came from what mech (unless you are installing brand new ones). You will see why this matters later in the guide.

Then loosen the set screws and pull the flipper back through the top of the playfield.

Next, remove the Coil Stop screws. There are (or should be) two backing nuts on the backside of the Coil mounting plate. Don’t lose these nuts, or let them fall into the machine.

If the nuts are missing, replace them with 8-32 nuts.

You don’t actually have to remove the the mounting plate, or unsolder the coils to rebuild the flipper mech.

Here is a typical, damaged coil stop.

Note the rolled up edge that causes the plunger to Mushroom.

As the Coil Stop becomes worn, it becomes thinner. When it becomes too thin, the Plunger Link will start hitting the bracket and be destroyed.

Don’t mess with trying to fix it, just throw it away.

Here is a typical, damaged coil stop.

Note the rolled up edge that causes the plunger to Mushroom.

As the Coil Stop becomes worn, it becomes thinner. When it becomes too thin, the Plunger Link will start hitting the bracket and be destroyed.

Don’t mess with trying to fix it, just throw it away.

Here, one of the Flipper Coils looks burned.

It tested OK with a meter, and the Coil Sleeve easily pulled out from it.

I was surprised, usually Coils that get too much heat will melt, making it difficult or impossible to remove the Sleeve.

Since the new Sleeve slid right in, and the meter said it was not shorted, it went back into service.

The Coil Sleeves are a very important part of having powerful flippers.

The old sleeves are made of metal, and thus have more drag on the plunger than the newer Nylon style.

ALWAYS throw the old metal ones in the trash. Don’t clean them, don’t burnish them, just trash them.

Your new Nylon sleeve upgrade will give your flippers more power, and cause less wear on the plungers.

You of course got new Sleeves in your kit, but it’s good to know that they are the same Sleeves that fit most Pop Bumpers and Slingshots.

The Flipper Bushing is what keeps the flipper from dragging on the playfield and ruining it.

When you see games with two “angel wings” carved into the playfield in front of the flippers, you know nobody ever replaced the Bushings.

We, of course, ALWAYS replace the Bushings when rebuilding the flippers.

Even if the flippers are not dragging on the playfield (yet), they will often have too much play because the Bushing holes have become worn.

Remove the 3 nuts and the Bushing will pull right out.

The Bushings are attached to the playfield with 3 Fin-Shank screws, just like Pop Bumpers are.

If your screws are stripped, bent or corroded, replace them before putting the game back into service.

If one of these fails, or becomes loose, the flipper will chew up the playfield in no time at all.

Make sure the nuts are Nylon Insert Lock Nuts, and have not been replaced with standards – the surface of your playfield depends on it.

Here you can see the difference between an old style and modern style Flipper Bushing.

They are NOT interchangeable.

While newer style Pawls grip the Flipper Shaft with a C-Clamp configuration, the older ones have a pair of Set screws offset by 90 degrees.

Each Set Screw has a sharp point that deforms the metal shaft to hold it from slipping.

If you have a Torque Wrench, Williams recommends that you crank the Set Screws down to 75 lbs.

Here in this picture, we can see the differences between the older Flipper Shafts and the modern style.

Note how the Set Screws have dug a hole by displacing the surrounding metal into a mound.

Note the groove/keyway cut near the end of the shaft is deeper than the metal mounds.

This allows the Flipper to be removed, despite the mound of displaced metal.

If you ever put a modern flipper shaft into the older style Pawl, you will NEVER be able to remove it. The mound of metal will cause it to permanently bind, and you will have to cut it out.



Because the shafts get permanent holes in them from the Set Screws, that is why we marked which flipper came from which mech. The Set Screws “find” the old holes as soon as you begin tightening them.

Reassemble the flippers.

Remember to use the Flipper Gap Tool, to set the amount of clearance between the flippers and the top of the Bushings.

If you don’t have one, they are only $1 :

After reassembly, it is time to set the EOS Switch gap.

99% of all “my flippers are weak, even after I rebuilt them” complaints are from setting the EOS Switch incorrectly.

When the flipper is at rest (not energized), we need the EOS Switch to be TIGHTLY closed.

We do this by gently bending the two switch leaves towards each other with this tool:

Both leaves should have tension towards each other from bending.

There can be a few other switches ganged together behind the EOS Switch. These need to be separated by an insulator, or you can accidently send 28VDC down the switch matrix, killing it.

If you make a repair to a ganged switch, or lose the insulator – make sure the new insulator is made of something NON CONDUCTIVE.

With your finger, move the Pawl so that the flipper is fully plunged.

The insulated arm of the Pawl will now need to open the EOS Switch.

When fully extended, the EOS Switch gap needs to be EXACTLY 1/8″. Not more, not less.

A larger than 1/8″ gap will make the flipper weak, by shutting off the high power winding of the coil too soon.

A smaller than 1/8″ gap risks that the switch may just arc and not shut off the high power winding at all. This overheats the coil, and burns out the associated transistors.

You will need to play with the adjustment tool and bend the switch leaves a few times to get it perfect.

If ever you find a weak flipper that otherwise freely moves through it’s range of motion manually, suspect the EOS Switch. The contacts may be dirty, or the tension/gap is set incorrectly.

That’s it.

Now, with your Nylon Coil Sleeves, your flippers will perform better than they did when they came from the factory.


As great as the 80’s Bally pop bumpers are, the Linear Flippers are total crap.

The Linear Plunger is heavy, so much of the coil power is wasted moving the giant plunger.

The crank has a little button of Nylon that drives the Plunger.

Because there is so little surface area, the button wears very quickly.

Worse yet, even though we were told by Bally distributors that the buttons were to be sold separately, that never happened. You had to buy an entire new crank.

The cranks are expensive ($12), and the entire rebuild kit is around $70!

So we already have a weaker flipper because of the giant plunger, now let’s add in lots of slop.

The little Nylon Button wears quickly both because of the tiny amount of surface contact area, and because the slots in the plunger were poorly machined.

Looking in the slot, you will see lots of tooling marks that are abrasive to the Nylon Button.

The wear opens a gap in the slot, causing sloppy action. Again, the slop is robbing the flipper of power.

It’s hard to imagine a less robust flipper design; but Bally kept making them for a decade.

So what is the solution to the Bally Linear debacle?

Upgrade your flippers by downgrading to the previous generation of Bally flipper mechs!

That’s right, we are going to use the much stronger, cheaper, older design.

First, order the KT-BFLIP-03 rebuild kit from Pinball Resource ($44 after your 10% discount for ordering $100 worth of stuff):

DO NOT tell Steve you are modifying linear flippers, he will yell at you.

Then order the better Williams EOS Switch also from PBR : #03-7811

The Williams EOS Switch has the little helper spring leaf that makes a stronger electrical contact. Stronger contact means stronger flippers.

You won’t be using the Compression Springs or the EOS Switches from the kit.

The new Cranks have 3 cap head bolt holes in them to grip the flipper shaft.

We are going to hijack one of the holes to mount a little spring wing arm. The arm is just a piece of “L” bracket. This allows us to avoid the junky Compression Springs, and use the much superior Extension Springs.

Compression Springs ALWAYS break. They also scratch up the Plunger Shaft, putting more wear on the Coil Sleeve and transferring less power to the flippers due to the increased friction.

Wipe off the waxy protective coating on the new Plunger Shafts with Naphtha so you don’t contaminate the new Coil Sleeves with sticky goo.

Flip the coil orientation around so that the lugs are away from the Coil Stop. This will keep the vibration from breaking the fine coil wires off at the lugs.

Adjust the EOS Switch gap so when the Plunger is fully pulled into the coil, the switch is opened 1/8″ . Not more, not less.

Now when you play your downgraded Bally, you will have solid flipper control and better than new flipper power.

Since I always catch hell if I suggest doing a repair other than stock….

Pin-Logic sells a replacement button that you can put on the end of your crank.

$4 is a quick way to get a sloppy set of flippers flipping again.

Is it as good as switching back to old style mechs? Nope.

But it’s cheap, quick and it works!

30 years latter, we finally got our replaceable nylon button.

People often comment that they seem to have less range of flipper motion when really worn flippers are overhauled.

This is because worn coil stops change the range of motion.



Remove the clamping bolt, and file off a little material.

It won’t take much.

Classic Bally Early Solid State Flippers

The early Bally SS flippers were a pretty dependable design, so often when you buy a game, you will find all the parts completely worn out and crazy sloppy.

Here we will rebuild this unit, improving the EOS Switch (End Of Stroke Switch) and installing the coil in a more reliable position.

Label your wires and unsolder the 3 wires on the coils. Loosen the 2 set screws on the crank to release the flipper bats, and finally remove the 4 baseplate screws to release the mech from the playfield.

I’ll assume you have bought the Pinball Resource rebuild kit for the rest of this guide:

The Coil Stop gets pulverized into powdered metal, resulting in all that black metal dust you find all around the coils in your machine.

Here you can see how much wear has occurred to this Coil Stop.

The more the Coil Stop wears, the deeper the plunger enters into the coil.

The deeper the plunger goes into the coil, the longer the flipper stroke.

Often people get used to the super long flipper stroke of a worn out mech, and then when they rebuild the mechs to their proper function, they are surprised by the now more limited stroke.

A great many people have never experienced a Classic Bally with properly functioning flippers.

Just like the Coil Stop, here you can see that the worn out Plunger has also lost a lot of metal; and of course, that affects the length of the flipper stroke too.

The worn out link now has elongated holes for the Crank and Plunger. This results in lots of slop and power loss.

An E-Clip locks the Link to the Crank. These are often missing entirely on old games, resulting in yet more slop in the action.

An E-Clip is a type of spring clip. Be careful removing and installing them, as they will literally spring off and be lost forever in your shop.

If you don’t have an E-Clip tool, gently pry it loose with a small screwdriver. Have your free hand ready to block it, in case it tries to spring away.

Remember there is a Left and Right Crank that matches the Left and Right Baseplate.

The Coil has a Nylon Sleeve that the plunger runs inside of.

Never try to clean a Sleeve, just throw it away.

They are only .40 cents, and you can never get all the black imbedded metal particles out of them, no matter what technique you use. Your time is worth more than .40 cents, so to the garbage the old ones go…

You are going to install the coil with the solder tabs AWAY from the Coil Stop, so make sure you insert the Coil Sleeve as shown.

The new EOS Switch looks a lot different than your old one.

The old one had an extra leaf and a plastic barrel insulator.

The new one is much lower profile and has a piece of insulating paper called “Fishpaper”.

Your kit does not come with new Switch screws, so you will quickly find out that your old ones are now way too long.

If you have some shorter Switch screws #5-40, you can skip the following step.

With a small standard screwdriver, pry apart a few layers of the old EOS Switch insulators.

The old EOS Switch is probably so worn and burnt that you surly don’t have to feel bad cannibalizing it.

Here you can see that the old spacers have kept the mounting screws safely away from shorting out the coil.

Remember that the coil moves and vibrates – keep a good amount of space between it and the screws.

Back in Bally school, they used to tell us that it was important to keep the EOS Switch isolated from the mechs in those early SS games. Of course, 50% of all used games are all hacked up and are using uninsulated switches, apparently without damage to any circuitry.

Even though it may be unnecessary, most techs still want the insulator on the switch.

The other issue is that there is a better EOS Switch (#03-7811 also from PBR) in the Williams style.

This switch has a helper spring leaf that gives a tighter electrical connection, and thus stronger flippers.

The Williams style switch does not have an insulator, so we will add one.

You can buy a pre-cut Fishpaper switch insulator from PBR for .30 cents, or because you forgot to order them, you can steal them from the kit switch.

Pry open the switch with a small screwdriver or fingernail.

Here you see that the Fishpaper exactly fits the Williams switch.

The Bushing protects the playfield from flipper drag, and is important in keeping the entire mech feeling tight.

Don’t over-tighten the screws, or the plastic will break about a month or so latter.

It is always easier to assemble the mech on the benchtop.

You can use a #2 Philips screwdriver as a makeshift flipper shaft while you assemble.

Remember, we are reversing the coil so the tabs are AWAY from the Coil Stop. This helps keep the fine coil wires from breaking, resulting in a coil that ‘machine guns’.

Leave some slack in the wires that connect the coil to the EOS Switch. Remember that the coil vibrates, and we don’t want to stress the solder lugs.

Press the plunger down all the way till it stops with your finger, and make sure the switch gap opens to EXACTLY 1/8″ (3.2 mm). Not more, not less.

You may have to fiddle with the leafs to get them strongly touching when relaxed and 1/8″ gap when plunged, but it is a lot easier to do on the bench than installed in the game. You will get the hang of it, take your time and get this exactly right.

As the gap opens, the stationary half of the switch leaf should move towards the other contact. Literally the two contacts should always spring towards each other, not just limply touch.

If your flippers don’t hit absolutely hard when you power up the game again, 99% of the time you somehow messed up the EOS gap, and the contacts are not touching with enough force.

You can jumper the two leaves of the switch together with alligator clips as a test when diagnosing weak flippers, if the flipper now kicks like a mule, the switch is not properly making contact, is dirty, or is broken… least you know where the problem lies.

Make sure you install the left and right mechs back onto their proper sides and you are ready to play your game how the designer intended it to play.


Why the hell would anyone do something like that???

$22 future rebuilds, longer lasting EOS Switches because of Parallel Wound Coils, longer lasting Coil Stops, longer lasting links, no compression springs, indefinite flipper shaft positioning, or the only thing you had with you on a service call was WPC flipper mechs.

I went out on a service call to fix a Xenon that has been in constant service for 35 years. The clubhouse owner said the flippers were sticking in the up position, even if the power was shut off. This tells you that the problem is mechanical – flippers need a rebuild.

I had serviced this machine 100000 times, so I knew that the crappy Linear flipper mechs had been changed to the much superior Standard flipper mechs (how to do this yourself: ).

I brought a standard Bally rebuild kit ( with me to do the repair.

When I lifted the playfield I saw, to my horror, that someone had switched the game back to Linear flipper mechs! As a bonus, they drove oversized wood screws through the coil stop baseplate holes, completely stripping out the baseplate. Normally if the base plate is stripped on a Classic Bally, you can switch the left and right plates to use the fresh holes (Bally are universal plates), but this trick had apparently been done already. If I was back in the shop, I could drill out the holes, tap them for the next size up bolt, and get things working again, but I was 40 minutes from my shop. The only solution I had with me was WPC flipper mechs….

In this job I used:

You need to order right and left flipper mechs because Williams are NOT reversible.

You want the F-11630 coils because they are perfect replacements for the old Bally coils. Yes, if you “do the math” the F-11630s are stronger coils than the Bally, but the Bally is only running at 43V, not the Williams 50V. The lower voltage nicely balances out the stronger coil.

You want the A-12111 coils stops so the flippers still have the same range of motion as the old mechs.

You want the High Voltage EOS Switches so they don’t get destroyed by the spark arc. The new Parallel coils will cause less damage to the EOS Switches, but will still be too damaging to low voltage switches.

The new Parallel coils are wired differently than the old Bally Serial ones.

The new Parallel coil has the Power lug on the left. You know it because it has both the tiny Hold wire and the thick Flipper wire.

(The old coil Power wires were not even soldered! Nice work bozo.)

It’s always best to do all the bench work on a bench, rather than dripping solder all over the machine.

Wire up the EOS Switches to the proper coil lugs.

Remember this is a Parallel coil, so the Power lug (the one with both a fine and heavy coil wire) does NOT get connected to the EOS Switch.

The lugs on this coil were smaller than the Bally coil, so I wrapped the EOS Switch wires BELOW the lug eyelets. This leaves the eyelets open for the Power and Return wires. Having open eyelets makes soldering under a playfield much easier!

Remember that the coils are mounted with the Lugs AWAY from the coil stop!

Stick a #2 screwdriver or flipper shaft in the mech and set up the EOS Switch gap.

1000x easier to do on the bench!

Details here:

Before you put the playfield mounting screws into the new flipper base plates, you need to be sure that the Flipper Bushing stays in the center of the playfield hole.

You won’t be able to hold it by hand; the force of the screws making new holes will drag the Bushing in some random direction.

There were a bunch of light tubes that are supposed to go behind the Xenon drop targets, that were just lying in the bottom of the cab. I used one of them as they fit snugly in the playfield holes.

After I screwed down the baseplates, I twisted out the light tubes.

Had the tubes not fit snugly, I would have had to EVENLY put a few wraps of electrical tape around them.

The baseplates can be spun in any direction to avoid inserts or other obstructions under the playfield. Both baseplates don’t have to be at the same angle or aligned with each other.

Unscrew any wiring harness clips that are blocking the new base plate. You can re-attach them latter.

You want to reinstall actual Bally Flippers because Williams bats are thinner and the ball will hop when coming down the return lane.

The worst part about Bally flippers is that any previous installation will make a memory dimple that will keep you from changing the alignment of the flippers.

If you try to move the flipper’s resting point down a little, the set screw finds the old dimple and pops it back into the old position. Even if you swap the left and right flippers, some pawls still find the old holes. It sucks.

The new Williams pawls will grip the flipper higher on the shaft, above the old holes.

You can freely change the flipper alignment, now or years from now.

Your new mech now has the coil mounted 180° around from the old coil, so don’t let yourself get confused on the wiring.

You might have to snip a few nylon zip ties to have enough slack in the wire to reach the new coils.

The Power wire chains power from one flipper to the other, so it is often doubled up on the Left flipper.

The Power wire goes to the “empty lug” (the one with a heavy and fine coil wire leading to it).

The Return wire goes to the outside lug that already has an EOS Switch wire on it.

You can always check for 43VDC with your meter to find the Power wire should you find a game with the flipper mechs missing, odd colored wires spliced in, or whatever other mess you encounter.

Work the mechs by hand and make sure all the wires clear the moving parts.

Zip tie all the wires out of harm’s way.

If you find that the flippers are a little too strong, simply open up the EOS Switch gap by another 1/16 of an inch or so and you will find the power drops substantially.

If you find the flippers are weak, you know you don’t have the EOS Switch set properly. The contacts need to STRONGLY close towards each other.

Here was the final installation.

Question: I have tried searching this thread for the answer but if switching to the WPC plates, what coil stop is correct?

Answer: A-12111

Question: How do you determine this?

Answer: You want the flipper to have the same range of motion as it originally did.

So you have to find the matching Coil Stop.

BUT your old Coil Stop and plunger will be worn and have MUCH more range of motion than when new. So when you are finding the matching parts, you have to use all BRAND NEW parts of the old mech.

Question: Is it the same coil stop # that would go into the stock flipper assembly?

Answer: Not necessarily.

Williams changed the coil stops in the 90s to make it harder to catch and cradle the ball.

Question: I have some plungers that have what looks to be a black coating on them. Is it OK put these in a drill and buff them up with Scotch Bright and polish them with Mother’s mag cleaner until they are shiny silver? Is the coating just a build up of the black dust, or an original coating to reduce oxidation?

Answer: Probably time to replace your flipper plungers.

Some Bally plungers have a Black Oxide finish when new, but if you can tell that the plunger used to be bright metal, and has oxidized to black, it’s easier and cheaper to replace them.

You never know what parts, from what source or brand, the last 10 owners of the game have installed.

A complete flipper rebuild will bring you back to better than new performance, for very little money and time.

Question: Is there a parallel equivalent to this coil: SG1-23-850-DC?

Answer: Usually, only flipper coils with dual winding are available in Parallel.