Congratulations on your machine. Working on these is fun and rewarding, but there is a learning curve.

Do you have the schematic? Have you checked out the sites that go over the EM pinball tips on the steppers and switches?

I’m attaching a clip from the schematic showing the race step up coil. The key switches are an end of stroke switch on they advance unit and the contacts on the advance unit on the last position (10). It’s possible that the contacts on the stepper are dirty or misaligned, same thing on the end of stroke switch. Since you can get it to work sometimes, that’s my guess.

Good luck, it’s a fun game.

Dave

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Sounds like the stepper unit is gummed up if you hear it try to move and it does not.

See this guide for cleaning them:

http://www.pinrepair.com/em/index2.htm#steps

There are also ver good videos on YouTube showing how to disassemble, clean, and reassemble the steppers. When they are clean they step along nicely like a clock. When they are dirty, they give you all sorts of problems.

The race unit must be resetting ok, otherwise the game would never start.

Dave

Well, I’m not sure how to give you confidence, but I can tell you that as long as you don’t manhandle the parts, you really can’t ruin anything beyond repair. If the game doesn’t work, you’re not going to get any enjoyment out of it.

If you think the mechanism is free enough to work, then you should focus on the 2 switches that I outlined. If they are dirty or not making good contact, it would cause the problem you described. It could also be a bad solder connection at the wire tab (because you report that it works with the playfield up). If you need help with the wire colors, they are in the schematic, and I can point them out.

If the race unit step up coil is getting energized and not stepping up, then it’s a mechanical issue and you’ve got to clean the unit. It’s really a process of taking lots of pictures, carefully removing the springs and fasteners and keeping them organized, cleaning, and reversing the process. Fortunately, there is a ton of documentation on those Williams steppers, lots of pictures online, and lots of people who can help you out if you don’t put it back together right.

Your other option is to find a local service guy or pinsider to make a house call.

Dave

There is a balance on the reset spring between when it has too little tension and can’t return to the zero setting when the reset fires and when it has too much tension and can’t step up when the step up coil fires. It’s usually 3 turns, but the hook that goes on the gear allows you to fine tune the tension by less than a turn. You should be able to work the coil plungers by hand and observe it step up, and then pull the reset plunger and see it go back to zero. If there’s dirt, or old grease on the spider contacts or the Bakelite plate with the copper traces on it, then there will be more drag that can cause sluggish operation. When it’s clean and lubed with just a touch of superlube, it will step up nicely and reset to zero from any position.

Re: flipper set screws. That can happen, especially if the flipper shafts have divots worn in. Then and you try to align it just a little further away... the screws want to fall back in the old holes. Again — it’s a careful balance. You can’t crank those screws really hard or you will break them off, but they have to be tight or they will loosen up again. Try tightening them slowly, going back and forth between the two, to lock the shaft in place.

Dave

That’s a pretty common problem. You can get screw extractors at the hardware store. The trick is getting a drill bit in the center of the broken screw and deep enough for the extractor to bite. I have successfully saved 2, but there was one that I just couldn’t get centered. You can get a new crank piece from either pbresource.com or eBay.