Everyone is leading you in the correct direction. Here is a photo (thanks xsvtoys) showing the credit unit and the switch stack of interest. For the Bon Voyage and similar age machines, the credit unit end of stroke switch stack for the knocker is at the bottom of the photo. The feed voltage is the yellow wire and the switch makes contact with the Blue-Orange wire. Check this switch. Your colors may vary. If cleaning or slight adjustment doesn't fix it, start looking for other issues. This is a simple circuit.