Thanks for the response.

So I checked the check valve and it appears to be working, I think. No air coming from that end.

By the I opened the switch box to blow it out and now got it to cut-in at 90psi and cut-out at 125psi.(factory specs)

So, when I first started the day the compressor again wasn't shutting off but then began to shut off. Not sure if this is due to the leak. So I brought it up to pressure, it shut off and I can hear and feel air but can't figure where its coming from. There is no tube going into the switch box. I then did the old plumber thing(soapy water) and sprayed carefully. No air from any connections, then I sprayed the front of the switch box and sure enough, big bubble coming from the square gasket where the aluminum connects to the plastic box.

Now, can this be fixed? Held in with 4 screws , but I do not see anywhere where this gasket is sold separately. The switch seems to be sold as an entire unit. Can I buy this gasket? Can I make this gasket? Can I use some kind of gasket sealant? or just buy a new switch as my intermittent cut-out problem might be due to another issue.

Thanks for reading.