Could you suggest a way to just bypass the controller and run at full
power?


get a rectifier of lets say 5 amps or morw and can handle 160 V AC or
better.
P.S.
if you really don't know the actual max voltage to the brushes you
could burn out the motor giving it direct source via a rectifier.
you will know if it seems to really wind up faster then normal before
the smoke comes out.
oh btw, legion has it, if you let the smoke out then its a total lost!



He said it hums though and measures 100v at the motor? That would seem to
indicate that the speed control is fine (heck he replaced it right?) perhaps
it got overheated and demagnetized the field magnets? I can't think of
anything else that could be the problem unless the thing is physically
jammed or he's measuring wrong.