Andy wrote:

1. Check the thermal overload. Remove it from the circuit, and find a
way to load it up with a known current until it trips. It should trip
after some time at 1.15 times the nameplate current. It generally
takes a long time, like several minutes, at that current. This will
be around 2x the motor FLA. If the overload trips before you reach
1.15x, then the overload is bad.

I'll try to check it, but the thermal overloads I've dealt with in the
past usually don't reclose quickly. In this case, the motor stalls,
the unloader releases, and the motor restarts inside of about 5
seconds...and then the cycle repeats.

But, it's looking likely that I need to take the motor apart and
inspect the innards (or take it to a motor shop.) So, I'll certainly
check the overload(s).