Williams Big Ben (I actually find the game quite fun) has worked great until just recently.
Like the Post says, the end of ball bonus does not score. The counter unit attached to the playfield appears to operate just fine. When I knock down the drop targets for double bonus, the points score just fine.

No loose wires. Bonus and Double Bonus make-or-brake switches are good.

I assume it has something to do with the stepper unit in the cabinet, but I have no schematics, and the IPDB does not have very clear schematics.

Any experts have ideas? I've poked around for a couple hours, but no dice.

Thanks, everyone.

It does go through the motion perfectly. The lights trip down, and the bonus unit trips down. No score, no chimes.
On Double Bonus, it chimes and scores as it should.

Morning bump?

I had a minor adjustment on the last contact switch of the Advance Relay. It was closed, and should be open. Also, I vigorously cleaned all the switches on the make-or-brake Bonus and Double-Bonus relays.

Thank you for your help, Rolf!
Excellent assistance.