sounds to me like the wiring is messed up. the game should coin up and play, if not the wire for the coin and credit switch just inside the coin door is not connected properly. It is either the filter board (on right side of cab from back door) or the wires to the edge connector from that board is mucked up. Pics of the wiring to and from the edge connector and filter board would help. Also pics of the credit button to the pcb would be good also.