Okay, tell me what I broke!
I took my scooter out today and the speed was variable, even in full throttle. It started surging, then going slow, then surging, then going slow. In just a few minutes, it wouldn't get over 15 mph, even in power mode. After a while, it wouldn't go at all, and there was the smell of something burning that you probably don't want to breathe. I parked it and brought it home in a truck (fortunately, I was a couple of blocks from home). On last check, turning the throttle made a clicking noise, but didn't turn the rear wheel. It still rolls, but not very easily.