LOL! I know that uneasy silence and the cursing. Especially the cursing! My cursing also sometimes comes with non-silent problems.
I would definitely say keep playing with the belt. It's tiny tiny little adjustments with that machine. Sometimes it's hard to tell there was a change between too loose and good and too tight.
One of these days I'll get Ronnie out and use the digital thermometer on her to see what temperatures she gets to. I know it's usually her pedal (in need of adjustment) that gets warm enough for me to stop first, not the motor.
As far as the no sound at all when you step on the pedal, I agree with David. This can be tested, but requires you to take the motor apart to do it. I would say if it's livable,... leave it alone.