Are you sure it's the motor bearing?
I had a problem with my furnace about six years ago. The shaft was chewed up right where the squirrel cage's set screw touched.
It squealed like Steve Ballmer on a canoe trip, unexpectedly pressed into entertaining hillbillies.
The solution (someone else's idea) was to move the shaft in the motor so that the squirrel cage is no longer on the chewed part.