Issue: The General Yagov kicker is not working at all. This part adds a lot of playing fun (the kicker slams the ball back brutally to the player), so seeing it work would be nice.
Solution: At that time, Williams didnt use any TIP36c transistors to drive high power coils. They used regular TIP 122 transistors to drive whats called a "snubber board" - many variations starting with C-11232. The snubber board, basically a relay, would then energize and complete the groundpath for 50v to drive a high power solenoid.
Heres a picture of a snubber board -
Furthermore, there are no schematics of the snubber boards around in the official manuals. One gentleman from german flippermarkt.de draw one a while back -
Suspecting the Snubber board to be the most likely culprit, i swapped it with a known good one - nothing. You could hear the relay clicking, but thats about it.
Next check was to make sure that 70v are actually there. Hold one lead of the DMM to GND, the other one to +70v lug, and 70v was there. Last thing to check was the coil and the wiring to the coil itself. Getting to the coil itself is a real p* in the ass, basically all of the ramps have to go. Once there, the coil was taken out and measured. An intact coil for that location should measure around 4 ohms, the one i had measured around 3 megaohms - the coil was basically open. Replaced with a known good coil brought the kicker back to live.