Aha! Usually the fix for that is to gently bend the left rail over to the right a bit, until sensor test shows that it is reading consistently. But whatever works!

If you have an SE, that error message is a bug - I guess that's why they call it a beta version! I assume it will be fixed and a new beta released soon.

Pull hard on one or both of the top corners of the monitor, and it will pop right out and swing out of your way on an articulated arm. (It's held in place by strong magnets, just tug until they let go.)

I'm assuming you tried pushing the switch in manually in switch test, right? Like, with the eraser end of a pencil from above, or with something slid in from the side from below, and pressing it down? I've seen a couple of people here early on (none recently) mention a switch that was just mis-adjusted so much that a ball resting on it didn't quite actuate it. That can be fixed by gently bending the end of switch actuator arm up a bit, so it's pressed down harder by a ball. Maybe just something else to try before breaking out the soldering iron. Microswitches do very rarely fail, as they said.

It would be weird for all those LEDs in the bottom of the guitar to all fail at once. I'd be looking for a plug that's come unplugged, or a fuse that has blown.

What he said, but the board it's complaining about is the one inside the cabinet over by the tilt bob.

So is it the main (insert, GI) lighting that doesn't work? Or the hotrails? Or both. If it's both, I'd concentrate on the USB cable - swap in another cable, try a different port on the CPU side, etc. But if just messing around with the USB cable makes the board reset and go through its startup self test like that, then I'd also be looking closely at the power connector for bad crimps, pin not inserted fully into connector, etc.

Sorry to be so annoyingly persistent, but specifics matter. When you say "reseat the wiring harness" do you mean disconnect and then reconnect? And does this include the power connector (the two pin connector with red and black wires)? Basically powering it down and then powering it up by disconnecting and reconnecting the power connector will have exactly the effect you describe - all of the lamps will cycle through a reset sequence, but then go out again.

If they were all frozen before you did this, and stay all out after you did this, that speaks to an issue with the USB cable. If you don't see any obvious problems with the way the USB cable is connected at the controller board, or at the PC, then I would try replacing the cable as a first step.

IF however, by "reseat the wiring harness" you just mean wiggling the cables going to the board, and it does this reset, then the problem may be with the power connector itself in the harness.

I suppose you can never rule out a flaky circuit board but this still sounds like a USB cable problem. Have you checked the other end of the cable, at the PC box in the head? It can be hard to figure out which one it is, but if one isn't plugged in all the way, that would be your culprit. Or just unplug every one and plug them back in to make sure. And that doesn't fix it, next step would be replacing that cable entirely with a new one.

Nothing with this game specifically., but just historically on pins with backglass locks like that, the locks can partially block the channel even when "open", the lock cam screw can come loose and not allow it to spin when the lock cylinder does, the edge molding on the glass can slide partially off and block the channel, the head can be warped slightly and not allow the glass to feed into the channel, and about 12 other things. Usually with some wiggling, some careful "convincing", some looking in past the glass with a flashlight, maybe some careful application of makeshift tools (putty knife, etc) you can get the glass out despite the obstacles and then, with everything open, address the problem so it doesn't happen again.

Switch 17 (the standup target right below the bottom bumper) and switch 18 (the switch behind the rubber ring to the left of that target) will both do what you are describing if they are gapped too closely. Go into switch test and bang the playfield with the heel of your hand, or use the + button to have the shaker vibrate the playfield for you, and see if either or both of those switches close intermittently as you do that. I'm betting that's the problem.