Ok so this is solved. The good news is at least as far as I can tell the Sanwas don’t go bad after only a year of use. This was a wiring issue with some of the connections I made between the five wire harness and the wires to the usb encoder coming loose, ironically and randomly several at a time. I don’t always supervise the kids’ use of the arcade so it is also possible this wasn’t REALLY random, maybe one of the kids was particularly rough or lifted up the control panel lid and pulled some of the wires. All fixed up now! Now I have a few extra Sanwas for spare parts though! (Only figured out it was a wiring issue once I installed the new joysticks and problem was still occurring...)