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Williams "Black Knight" pinball restoration.
WPC style flipper upgrade
Nothing, and I mean nothing, can ruin the play experience of a pinball machine more than bad flippers. Ok, this isn't technically true, because a dead CPU does cause a bit more problems, but bad flippers really do spoil things pretty badly. Given that this machine is 30 years old at the time of restoration, and has obviously lived a hard life, these flippers are shot. Strength is inconsistant, but generally weak. They don't cradle very well. Sometimes the top-left flipper just doesn't flip. They even sound crappy, with a chunky, clunky noise to them. It's time to do a rebuild.

BUT!, (And there's always a BUT with me, isn't there), these flippers aren't that easy to rebuild. For this era flippers they integraded the coil stop into the baseplate, and it can't be replaced separately. What is the coil stop? I'll explain that later, but it's important, as it get mashed by the plunger every time you hit the button, and in time it does wear out and need replacement. Not easy to do, if it's not replaceable, you need a whole new baseplate.

Clay's amazing website over on pinrepair.com explains briefly how to update a System 3-7 flipper with WPC style mechanicals. Why do this? Well, Clay says that it makes them better performers, but I don't quite agree that it's such a big change in this case.. Mechanically, other than the coil, the non-fliptronic WPC flippers work almost identical to the System 7 flippers I'm replacing. The only real difference is that I'll be using a different style return spring, which will help, but not be a big difference.
So, why did I do this? One is to get that replaceable coil stop. I don't expect to need to rebuild these flippers again in home use, but the ability to do so is nice to have. However, unexpectedly, it also ended up to be cheaper doing this method. The difference was only a couple bucks per flipper, but I did have to do four of the things, so it adds up.
I started by using the parts list provided by Clay over on pinrepair, but when I tried to make the order I noticed a couple discrepencies. I couldn't find the EOS switch bracket available as a separate part, but then I noticed in the photo's that it's already included as part of the WPC baseplates, so there's no need to worry about it. Here's the parts list you'll need for each flipper. I ordered all of these from Pinbal Life, as they are reputed to be the ONLY source that actually supplies the exact parts you want, and doesn't make substitutions that are "almost" correct. Oh, I also snagged one of their kick-ass "PinGulp" cupholders. Highly recommended.

Flipper Baseplate, with EOS switch bracket: -16103-R (Right) or -L (Left)
Coil Bracket: 01-7695-1
Coil Stop: A-12111
Flipper plunger, link,pawl assembly: A-15848-R (Right) or -L (Left)
End Of Stroke (EOS) switch, normally closed type: 03-7811
Coil Sleeve: 03-7066-5
Flipper Bushing: 03-7568
Return Spring: 10-364 (Pinball life calls this a flipper extension spring).
2x: 10-32 x 3/8" button head screws, plus lockwashers

Optional Parts:
Flipper bat, yellow: 20-9250-6 (not really needed, unless yours is too faded or broken)
Dual flipper leaf switch: SW-1010A (Recommended, but not actually part of the flippers)
Here is one easy to spot sign, other than sloppy play, that it's time to replace the flippers. The one on the right here is obviously sagging down, which is caused by a number of problems, and likewise causes a number of problems during play.
I removed everything but the coil when I disassembled them from the playfield, as I just didn't want to deal with cleaning up the wiring tabs on the coils. The coils themselves I just left hanging there until I re-assembled everything. Probably not the best choice, as I eventually have to redo all the crappy solder joints currently on the coils, but I can always do that later.

Here is one of the removed baseplates showing what to look for when judging if they need to be replaced. One issue is that there appeared to be some kind of white lithium grease that smeared all over the place on the baseplate. These things do NOT need to be lubricated, that's the entire point of using a nylon bushing, in that it's self-lubricating.

You can also see how the coil stop has mushroomed out, which I circled for those who are still learning the nomenclature of pinball parts. On later (and earlier) versions, this part is replaceable on its own, but in the case the entire baseplate needs to be scrapped. A big waste of otherwise good steel here. This doesn't cause a huge amount of problems with performance, but still has an effect, which makes it even sillier that it ends up costing so much more money and effort to address this minor big of deformation and wear.
This is a more serious concern with wear, and is the biggest detrement to gameplay, which is why these things are in all flipper rebuild kits. this is the plunger/pawl/link assembly.

1: Look at the wear in the plunger shaft, which causes misalignment issues that results in the plunger dragging in the sleeve and the old return spring, slowing it down. This wear is actually caused by the return spring, and is why I switched to a different style spring, to eliminate this problem. If it wasn't for this wear, I'd probably just replace only the link here.

2: The link you can see that it's worn all over the place, mostly in the center hole which has become enlarged. This causes the flipper to slow down, but also means it won't flip as far up either. This again reduces strength, but also makes it much much harder to cradle the ball. You can actually hear this when it gets bad too, as it rattles audibly when flipping. Instead of a crisp "Snap" noise, you'll hear more of a "crunch".

3: This is where the pawl hits the baseplate assembly, and over time causes wear to both pieces.

In all, this section is a loose and floppy mess that results in the most problems in performance.
Why replace the EOS switch? Here's a good example why. 30 years of sparking across this gap has caused a lot of pitting and erosion of the tungsten contacts. A lot of non-functioning flipper issues are caused by this switch, and is one of the first places to look if diagnosing an extremely weak or overheating flipper.
All the shiny new parts lined up on the bench, after inventory. Not that the EOS brackets are already assembled to the baseplates, which is how they arrived from Pinball Life. It's a nice touch, and one less part number to worry about.
Most of the screws and washers you can re-use from the old flipper units that you are removing. The one exception is the screws that hold the coil stop to the baseplate. 10-32 can sometiems be hard to find, and you'll likely not find them short enough at a local hardware store. I could only find 10-32 x 1/2". They were very close to being too long, though would probably work unmodified, but I chose to cut them down flush using a cutoff wheel on my dremel.

Always spend the extra money to get the fiberglass backed cutoff wheels, which are the bigger black ones that have the grid pattern. The smaller brown ones, that come in the little tube, are too easily broken up and don't last very long before they shatter. Always use eye protection when using either one though, as they can throw minute particles in a lot of surprising directions.
The lower playfield flippers were a simple case of remove, re-assemble, and adjust. A real no-brainer. Though I recommend only doing them one at a time, that way you have another assembled flipper to use as a reference.

Upper playfield flippers were a different story though, as there were a number of clearance issues. This screw was very tough to access, and I had to strip down the whole flipper to get it out. Then when re-assembling, I had to install the bare baseplate first, and assemble the whole thing while on the back of the playfield. Not overly hard, but time consuming and slightly annoying.
Since you're probably going to ask, I used a 1/4" open ended wrench to get this one out. Every other one of these screws I just used a 1/4" nut-driver which is much faster.
One thing that I didn't realize until doing the upper flippers is that the WPC style baseplate is actually about 1/2" longer in the area that the coil stop attaches. It didn't matter with the lower playfield, as there was a lot of room, but the upper playfield needed some parts moved due to clearance issues.

The switch for the mystery ramp shot was easy to do, I just slid it over about 1/2" to the right, while making sure that the linkage to the wireform on the ramp was still vertical and had no clearance issues. Though you need to do this after installing both baseplates, in order to make sure it fits.

Harder to see, and harder to adjust, was the light bracket for the upper left drop target arrows. This took a fair amount of bending and trial fitting before I was able to get it all re-mounted. I kept running into the problem of the lamp glass touching the flipper baseplate. This will very quickly kill this lamp due to vibration, and they must not be allowed to touch.

Here you can also see a fully assembled flipper including the new style return spring. The old style wrapped around the plunger shaft causing the wear shown above. This style doesn't contact the plunger at all. System 6's and 7's you can just re-use the old coil, which I did as you can see. System 3's and 4's you also need to replace the coil too, as better described on Clay's website.
One area that I dropped the ball was taking more photos of when I was removing and re-assembling the flippers. I honestly meant to, but totally forgot. So instead of happy photos, you get a block of text instead. If I ever do another flipper rebuild, I promise to take photos here.

Removal is simple really, but the sequence is critical. I started off by loosening the 3/8" nut on the flipper pawl, and then pulling the actual flipper out from the top of the playfield. You'll want to use an open ended wrench for this, instead of a socket, as it's just easier to fit in among all the wires hanging around. If you are going to be replacing the whole assembly, including the coil, at this point you can just clip off the wires at the coil and remove the whole plate as one unit. But I prefer to leave the coil attached to the wiring harness if you can, as it reduces mixing up the wires on it.

The procedure I used from here on was slightly different, as I partly disassembled the whole flipper mechanism while still on the playfield. I started with the two phillips screws holding on the coil bracket, which let me remove the coil, plunger mechanism and spring. I left the coil hanging on the wires, clipped the two wires leading to the EOS switch and then removed the baseplate.

With the baseplate on the bench, I removed the old EOS switch and bushing, but only because I needed the screws and the EOS swtich backing plates. Using these screws I attached the new bushing and EOS switches to the new baseplates, as well as the coil stops as described above. I also attached the new return springs to the EOS switch bracket, which has a little hole for just such a purpose, with the other end of the spring going into a similar hole in the arm of the pawl assembly.

This partial unit is then screwed back onto the playfield. The plunger then needs to go through the hole in the coil bracket, before getting inserted into the coil (with new sleeve already in it of course). You can then attach the coil bracket to the baseplate, locking the coil in place. Re-insert the flipper from the top of the playfield, making sure to adjust it properly, and tighten down the 3/8" nut on the pawl. Solder the new EOS switch into place, and adjust it as well. It should be fully closed when the flipper is at rest, and 1/16" to 1/8" of a gap should be present when the flipper is fully flipped. It's easy to see if it's adjusted properly, as the flipper will move briskly, and you will see a bright blue flash at the EOS switch when it opens on most flips. If it doesn't flash EVERY flip, that's ok, as long as it's doing it regularly.

One last update I did was new leaf switches for the flippers. These were an easy remove and replace job, with a quick adjustment to make sure they open and close properly. The flippers may not work the first few tries when you install a new flipper switch.
Assuming they are adjusted properly..... If this happens, take a piece of paper and insert it between the contacts on the flipper switch and then hold down the button.... with the machine OFF of course. Slide the paper back and forth a few times to clean off any oxidation that may be present, and try again. Flippers should now work.

To Be Continued!

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