I have a 60 gall air compressor from northern tools and the electric motor stops at 30psi almost like it is struggling before it stops and trips the red rest button, I can see electrical sparks or arching before his happens. I removed the small air line going to the pressure cut of switch, it helps it run smoother, but the motors still stops, it has 220 volt power source w/a 30amp breaker. I can turn the compressor by hand when it stops, I am trying to determine if the problem is in my compressor or in the motor, if there is no air pressure in the tank the motors runs fine, any suggestions?