hi I've had a similar kind of problem as you in the past with my seally compressor. It sounds like to me that you have more than one problem maybe!! Firstly leaking pressure switch. I had the same thing it turned out to be just dirt and crap inside the switch which I cleaned out. once I removed it I also gave the non electrical moving parts a squirt with WD 40 after that it was fine!!

Compressor unit. it sounds to me like your non return valve to the tank may be stuck open hence filling the cylinder with pressure explaining why it will not turn over until tank is drained and no pressure is present as long as you have oil in it and it's not heat seziing. both of these problems will cause the motor to overload and blow the fuse whilst trying to turn the compressor over!! also it is worth checking both the capacitors in the motor connection box to make sure they are both ok as if one goes down this can also cause the motor to overload and blow the fuse and can also throw the over heat cutout switch open which you then have to reset once it's cooled down enough. This is usually found on the motor connection box!!!

Hope this helps u out maybe.

Stuart