15 gallon 200 psi Mastercraft air compressor. Plug it in..fine but once you hit the on switch the motor hums or buzzes then blows breaker after about 5-8 seconds.Shaft still turns freely.Both start and run capacitors are working.The spring inside the check valve was broke so I'm trying to order one but will this solve the humming and tripping breaker?I've tried plugging into different outlets same result.Help please.

Model #058-9317-8
120V 15amp.one person has told me they think the bushings are shot so the motor wont spin

How can i do that if i cant turn the compressor on to put air in the tank to perform the test?there was air trapped in the check valve when i first unscrewed it.would a bad check valve cause this compressor to blow the breaker after turning on?