Ohming out your connecting is testin the continuity of the circuit. There should be a setting on your digital multimeter that will beep when you touch the two leads together. This will help you "ohm" or " ring" a circuit.

What you are describing sounds like a problem with the return line in the switch matrix for that group. All of the switches you described share the same return. Like you said, you would think at least one of the switches is working but if your return is missing you will not get any of the coin door switches to work. I beleive the rerun line for that set is A6J6-6. Check wire six on J6. I think its a black with two blue stripes. Code 066??? Not exactly sure on that though.

Either way I would suspect a problem with that return.

Explaining how to use a multimeter can be challenging. My best advice would be to head over to YouTube and watch a couple of short videos. It's a great resource and seeing it done is much easier to understand than trying to interpret posted instructions.

You'll be fine. You will figure out the problem. Take your time. Don't rush and try to enjoy fixing the machine no mater how frustrating it can be. Enjoy your vacation!