Tools, Sharpening and Power Machinery - Old Montgomery Ward air compressor won't start

Hi,
I am a mom who bought an old compressor for my son and there is no manual.
Riverside 13 gal.
We tried it yesterday it ran once, shut off at 120 psi and that was the end of it.
We found a pin hole in the tank too which I guess has to be welded.
We disconnected and reconnected and it wouldn't run at all.
We got it on craigslist so no recourse.
Any clues? Hope it isn't a total waste now.
My son thinks something may be stuck a motor shut off or something. Where would that be and could that be the problem?
thank you

Welcome to the forums! Did you bleed any air off, or did the pressure drop on its own due to the hole. Have you inspected the switch, yet? With the unit unplugged, undo the gray cover that houses the switch. Inspect the contacts. I suspect they may be worn or pitted. If so, it is a reasonably easy exchange and they are readily available at hardware stores.
The pin hole is an indicator of a weak wall. Welding may or may not help, as the surrounding metal may be fatigued.
Drain the tank to see what kind of crud comes out of it. If nothing comes out, remove the petcock and let it drain, with pressure off of the tank, of course.
Caveat emptor.

Contacts look ok my son said.
Do you have to take the whole thing apart to see if the switch itself is bad. The pressure dropped because of the hole.
The unit shut off at 125psi. My son had a hose attached and there was pressure. Then we heard the noise of escaping air and found the hole. My son thinks something punctured the tank there. Supposedly the guy we bought it from took it apart and refurbished it but i have no idea what he did.
All we saw was, he turned it on and the motor worked. He had no chuck or hose so we took his word for it, it worked.
But now you plug it in and just silence.
Any other ideas?
thanks

There is a small hose that leads to the bottom of the switch. With the thing unplugged, remove that hose at both connection ends and run a wire through it. It sounds as if that tube is clogged with crud. It is the tube that tells the switch to turn on and off with pressure. Let us know.

Dirt in the line to the pressure switch is a possibility as chandler has said.

The hole in the tank unfortunately is not repairable.
It would be extremely dangerous to try any repairs on a pressure vessel especially one that is corroded.
Pressure tanks are strictly regulated and anyone that tries to repair it could be liable if anyone gets hurt.

I would suggest that you cut your losses and don't spend any money on this thing.

thanks for your insight.
My son took the switch off and by-passed it and the motor and compressor went on. The switch pieces fell off and he is getting the switch back together. The unit is in great condition and not corroded at least on the outside. It looks like new.
I am thinking maybe go to Grainger or Harbor freight is near me in Albany and get a whole new assembly if he can't figure out how to put the switch back. I had called Grainger and they said they have compatible parts.
So we will see. There was nothing in that hose part it was clear he said.
thanks again:)