Thanks for the post Venom4728a!

This is a pretty typical problem. I would first look to see if the in-tank Check Valve is clogged up. This can happen due to particulates getting inside the pump (past the air filter) and can make its way into the Check Valve. The valve is a ball and spring valve that's threaded into the bottom of your manifold (in which the pressure switch and pressure gauges install into). I'd remove it from the manifold (AFTER you drain the tank of air) and see if the ball and spring are still there; if they're missing, that's your problem and you need to buy a new Check Valve. If the ball and spring is there, it just may be that there is debris in the valve obstructing air flow.

Below you can see a parts breakdown on this model:

mastertoolrepair.com/portable-oilfree-ai...401110-p-747274.html

Also, make sure your Belt isn't too tight or loose. There should be 1/2" deflection when you press down at the center point of the belt.

Lastly, it could be that your motor Run Capacitor is defective. You can take both cylindrical capacitors to an electrical supply shop or electrician and have them test the capacitors.

Hope this gives you a starting point!

- MTR