Air Compressor trips breaker under load. If I remove the belt the motor runs fine, spins freely as does the compressor pump. With the tank pressure empty, the compressor starts and runs fine. When it reaches 125psi, it shuts off and I hear the unloader valve hiss a small amount of pressure. When I then draw down the pressure to around 85psi, the pressure switch kicks the compressor back on and it tries to start, hums for a few seconds and trips the breaker. If I manually draw down the pressure with the switch off between 85psi and 50psi, it trips the breaker. However, if I draw it down to 40psi and turn it on, it will in fact start and run back up to 125psi. I suspect that the following are ok but am looking for advice before part shopping: - start capacitor is fine (runs with no load, from 0psi up to 40psi) - unloader valve is fine (hear it activate immediately upon compressor shutting off) - pressure valve? I think it may be fine as it kicks in at the prescribed 85psi and activates the compressor to turn on - Check Valve looks like the suspect, but I have no idea how to verify. Any thoughts?