Putting this here for others with same issue. Had a problem with my beloved Rhino yesterday. It stopped reading the axes or moving. The potentiometer would still work. After a little bit of troubleshooting, I realized that the emergency stop knob seemed loose in its housing. After searching in vain for a YT video of someone taking apart one of these beasts, I gave up and started removing screws. I started on the top, which was.. wrong. Eventually I moved to the back side. After pulling away the side I discovered the knob had loosened enough to twist a little every time I turned it back on. The two wires twisted around each other until eventually one pulled free of its terminal connector. Repair would have been simple if I'd had the same terminal connector. Instead, after trying forever to uncrimp it, I just gave up, removed the wire, soldered it to the connector and reinstalled. I did my best to tighten the emergency stop knob back up, but it's hard to get a good grip on it, and I could see having to do this again in the future.