[Richard]

My thoughts are generic, but may help.

You have a big air leak, so the pump runs a lot. The problem with the super quiet JunAir pumps is that you do not hear it run. I know I have one. I had to put an hour meter on it to see how much it was running.

I am guessing the pump has a thermal overload on the motor. So yes, if the motor gets hot enough to trip the thermal, then it will reset when it cools off.

If the pump ran for a long time, then the oil became very hot. One of two things could have happened. One, you boiled the oil out of it. Or, the cylinder/piston is worn and pumping oil. You did say you added oil a couple of weeks ago. My JunAir has never required oil between routine changes.

Do you have a surge tank that the pump feeds into? Have you drained it? Was there oil in the tank?

Can’t say if the pump is OK or not. Fill it with the proper amount of oil and see if it makes pressure is the only way to tell. If it does come to life, you still have to chase down the air leaks.