It could be either a motor or compressor problem. If the compressor is dragging that would put increased load on the motor, increasing amp draw which could of course cause a breaker trip.
A motor going bad would have the same symptoms.
I'm not familiar with this compressor, but if you can unhook the compressor either by removing the belt, if its a belt drive, or by what ever method is necessary, does the compressor turn freely? with perhaps a little resistance on the compression stroke? Does the motor turn freely when spun by hand?
with the compressor unhooked does the motor then power up freely?
The easiest way to do a preliminary test of the motor is with a clamp on amp meter, comparing actual amp draw at start up and running, with data on the motor name plate. that data should include maximum starting amps as well as load running amps.
The next step then would be to have a motor shop test the motor.
on a side note, several years ago, i had problems with a craftsman 60 gallon upright compressor (made by devilbliss) that kept blowing head gaskets on the pump itself. while under warranty sears replaced the gaskets several times and the valve plate once. The last time it happened i contacted devilbliss directly and they replaced the entire pump. That solution finally worked as to date, no more blown gaskets. To this day i'm convinced the heads on the pump were slightly warped but knowing how service on things like this go, service tech's generally think the consumer knows nothing.
