Sears Air Compressor Won't Stay Running

I have a 10+ year old Sears 2HP Air Compressor (model 919-176821) that starts and runs fine when you first start it with no air pressure in the tank. Once it
shuts off after coming up to pressure and then tries to restart to re pressurize the tank, it drags very badly blowing the circuit breaker. I can slightly lift up on the motor to release belt tension and can hear the motor run. I have checked and confirmed that the compressor oil is at correct level. Any thoughts as to what might be causing the problem and how to correct? Thank you
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On 3/28/2020 6:14 PM, David wrote:

There is a check valve of sorts that allows the piston pressure to drop after running. If it is holding pressure there is not enough power to move the piston.
On top of that, there is wear on the parts and possible drag as they heat up.
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90+% chance the unloader valve is stuck
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wrote:

Bingo. I would just buy a new switch with an unloader and be done with it $30 or so.
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