EM williams games with dimes/quarters slots do not "coin up" like you might think. If you insert a dime, it will reset the machine (without ever adding a credit) and the game will be ready to play. When there is a quarter chute, this will only add credits (according to the jumper you're missing) to the credit unit but it will not automatically reset the machine. To use those credits, you press the replay button. During reset, the machine will knock off one credit. The real kicker is that if you have credits (or replays) on the credit unit and insert a dime - the machine resets and steals one credit

I have a 1965 Williams that takes dimes, and quarters. It has both 10 and 25 cent relays. If I have credits on it, put in a dime, the machine resets and the credits remain the same.

If your machine does not have a 25 cent relay, I don't see how it's going to accumulate any credits. Someone must have cannibalized those parts for another machine is all I can guess. Surely the factory wouldn't have "customized" this machine by request.

if you don't have a 25c mech, then you have no use for a 25c relay, the adjust plug, or anything related to 25c.

the 10c coin switch is on the piece of the schematic you posted. It's just called "coin switch" and it powers the coin relay like gutz said. You need to look further down the schem to see how the "replay S.U." coil gets powered to see how credits are added. There'll be 25c relay/switch stuff there, but no "coin switch".

if your game is in an impossible state ... lock relay powered but the game relay is not tripped, the coin switch - and the replay button - won't work.

you need to debug the circuit thru the anti-cheat relay switch thru the coin switch to the coin relay.

fwiw, it's also likely your game works exactly as gutz said ... tho he probably should have said "some williams EM ...". sudsy7 has more complicated circuits and his machine will work differently.

Mine is a different machine than yours, but all these 110v control relays should be next to or very close to the transformer on the floorboard. You probably don't have the 25 cent relay in yours. It is strange that it would be on the schematic (with no dotted lines around it or any indication that it is optional) and not be in the machine. But apparently it was made that way, unless somebody modded yours and cleaned up the evidence of the crime scene very well.

What happens when you actuate the Coin Relay with a wooden stick momentarily?

Good point, my experience is with williams pitch'n'bat games from the early 60's.

The 25 cents relay is located on the left of the logic board, between the transformer and the score motor.

Bid Daddy 25cents relay (resized).jpg

You will like this game when you get it running.