Now back to that power switch and the hole in the side of the cabinet. After a bit of detective work and tinkering, I was able to remount the power switch on the volume pot and make it work - most of the time. Every 50 or so flicks the little wire stub wouldn't flick the switch over. When this happens, the only way to fix it is to remove the chassis and manually flip the switch. I suspect this is why someone relocated it to the side of the cabinet.
I've gone back and forth over what to do about it. Currently, I'm going to leave it mounted in the side. I'm not going to refnish the cabinet and any patch job I do is going to be very visible and I'm not crazy about having to pull the chassis next time it gets stuck.