PMFBI, but I have a very similar problem: Jacuzzi pump w/ 1.5 HP
Magnetek motor. The pump housing overheated once and malformed inside,
distorting the diffuser vanes inside and binding the impeller. Applied
power to motor and it hummed and smoked a little. Disassembled,
reheated and reshaped diffuser vanes so they clear the impeller. Shaft
turns freely, but motor will hum loudly before it starts. Once it
starts it seems to run and pump just fine. But on every startup it
hums and vibrates quite loudly for about 1 second and seems to be
drawing a helluva lot of current.

Before I disassemble it (again) to check the motor's start contacts
(which I suspect are probably welded shut due to excessive current), in
case I reach a point where I'd like to completely separate the motor
from the pump: how do you get the impeller off of the motor shaft of
these suckers?

Thanks.