Hey currie! Since the op says the score motor is turning, I wonder if that means the coin switch is OK since it's turning on the W relay (which starts the score motor). I wonder if there's a problem on the W relay, since there's a switch there that energizes the replay unit - or any of the switches in series with that m/b switch in the add replay unit circuit.
sof76 (resized).JPGsof76 score motor (resized).JPGsof76 replay (resized).JPG

It could also be a switch on the S relay not turning on the W relay, depending on how he has the 1st coin chute adjust set. Either way, the W relay has to be energized to add a credit, I think.

Hey DaMoib - yeah, I see that now - the W relay is skipped altogether when the 1 coin 1 play is connected and the #1 coin chute is used.

Yes, your motor 4C switch or motor 4B switch is probably not working correctly. Look at the schematic snippet below:

The 4 and 5 credit settings bypass those 2 switches - the 2 and 3 credit settings need them to make a connection, so I'd imagine that's where the problem lies.

sof76 problem (resized).JPG