"Wild_Bill" wrote:

The main problem is that the motor is being overloaded. As mentioned
already, induction motors don't get tired or exhibit lower power output with
age.

It's taken longer than I hoped, but I have finally put my air
compressor motor back together and it's working again!

To review, over time, the compressor had developed a problem of the
motor stalling before it reached full pressure.

Bearing in mind everyone's suggestions, I took the motor apart and
found that the bearings looked good, there was no sign of rotor/stator
contact, and the internal wiring and connections looked OK. The only
obvious problem was somewhat burned contacts on the centrifugal
switch.

Unfortunately, as I was taking it apart, I broke the voltage selector
switch, and that's what's taken me so long to get around to fixing.

Finally, with some JB weld and spare circuit board material, I managed
to glue the switch pieces back together.

I then cleaned and reseated all the internal connectors. I measured
all the windings for continuity or shorts (they looked good.) I
installed a new start cap, lubricated, and reassembled the motor.

It ran, but wouldn't start. After disassembling it again, and some
careful bending of the centrifugal switch, it was starting and running
smoothly.

Then, the moment of truth, I put the pulley and belt back on and fired
it up. As I carefully watched the pressure gauge, I kept adjusting the
regulator upwards. I ran it up to 140psi, and there was no sign of
stalling or even slowing down! Success!

I then adjusted the regulator back down to 120psi and buttoned
everything back up.

So, thanks to one and all for your help and suggestions. I'm back in
business!