Is the coin door OK? My later Midway rifle games have a 6/8 pin bakelite connector to connect the coin door.
The coin door has wiring for: coin switch, lockout coil, slam switch.
No credit button.
The rifle portion would have 2 wires for the trigger switch, 2 for the recoil solenoid, and one for the stylus.
Do you have the schematic? I imagine those plastic insulated wires would be depicted on there.