Got the screw out with one of those double-ended screw extractors. Yay! However...it wasn't the handle bar switch. There must be a short or something from the switch to the relay. I can do a continuity test from the bar switch to the relay, but is there any other in between I should test for first?
From all you've written, I don't think the problem is in the handlebar switch or its wiring. I think it's in the relay or in the cable connections to/from the relay, or the ground strap, which I've mentioned before.
It's easy enough to test this hypothesis: Jump 12 volts to the switch terminals on the relay. If (and only if) the starter works perfectly, then the trouble is in the handlebar switch or its wiring as you suspect. If not, then it is as I suspect.
That is true. I haven't completely ruled out the relay. This will have to wait until next weekend. I need more leads for my multimeter to test the relay, and hardware stores just don't carry that much anymore. Had to go with amazon.