This might have to go to a repairer but might aswell ask here first. I ran
my 3hp belt drive compressor for the first time in years to blow wasp killer
into the eaves of my house. The compressor was failing to cut out so was
either not coming up to pressure or more worrying wasn't cutting out when it
should.
I had a problem before with the valve in the top of the tank that takes the
supply from the compressor corroding and seizing but I seem to remember that
being the opposite ie it wouldn't run continuously.That was simply rectified
by unsiezing the valve.
Unless this is very simple I am going to have to take this for repair, the
question is where, I am in SW Herts.

Kevin