Wasn’t what I thought it was, just a burned RF jack. Cleaned up and put back together.
Did a few basic tests and everything was fine, but I didn’t have time for a full battery of testing. So, please message if you have any problems. Please be as specific as possible.
The problem I was on the lookout for was uncommanded firing, noisily, whether running or not. The interlocks- opening the lid- will still guarantee the tube turns off. This could be explained by the burned jack and no prob occurred after it was cleaned up for as long as I tested it, but I’d like to be watching it carefully for the next few days. If the tube fires like that again, we need to shut down the machine and unplug it from the wall, but I don’t think it will.