The path MAY be broken by those coin door wires. To one coin switch, there will be one black wire and the second (on the right) will be TWO black wires joined. Looking at the loose wires, I'd be checking that.

I think you may have it there Strangeways. I went and had a look on a NOS coin door for a wpc95 pin, on the one i have  the ground wire goes to the coin switches first then returns to the service buttons. you will need to strip the two black wires and twist them together and insulate them. then put them in a place where they wont get caught in the door when you close it.