Response from Jonathan: Jessica,

There are at least 3 things that must be true in order for the game to add a credit when a coin is inserted: 1.) The coin must fall entirely through the coin mech and not get stuck or fall into the coin return. 2.) The coin must trip a switch at some point as it is falling through the mech. 3.) The switch that the coin falls on must be wired up correctly.

So, start off by making sure that the coin is falling through the mech and not coming out of the coin return or getting jammed up somewhere. Once you’re sure that the coin is falling correctly, you then need to make sure that it is coming in contact with the switch. In the attached photo, I have circled in green where this happens on your particular coin mech. If your coin mech switch does not have the activator bar (which is about the thickness of a paper clip), you will probably need to replace the switch altogether.

If the coin is falling through properly AND hitting the activator bar triggering the switch and you’re still having problems, you probably need to check the wiring. I believe that the ground and coin wires should be connected to the two pins CLOSEST to the front of the cabinet. Of course, please check the switch as it should be labeled accordingly. Make sure that these wires are connected properly and are running all the way to the main harness of the game with no issues (i.e. frayed or damaged areas of the wires, breaks in the wires, etc.). Now, if you do all this and it’s still not working then it’s probably time to replace the switch. Hopefully after going through all these steps you will have a nice, working coin mechanism in your VS Duck Hunt arcade cabinet.

Hope that helps. Thank you for your question and good luck with your repair.

Attached Image: http://www.arcaderepairtips.com/wp-content/uploads/2017/06/nintendo_coin_mech.jpg