Compressor not shutting off at 115 psi

[bandslak]

a couple of days ago I was spraying primer on a few car parts and heard a loud "pop" or "boom" so I immediately stopped and shut off the compressor. A while later i started it up again and noticed the main pressure gauge only went up to about 90 psi instead of the normal 125 or so psi and the compressor did no seem to want to shut off. I manually shut it off and went away for a while. The gauge stayed at about 90 psi and I could not hear any air leaking. I have read a few other forums and am a bit confused as to the possible causes that range from replacing a number of switches (including the pressure switch) to possibly a blown gasket or baffle somewhere that may be preventing the pressure from getting above the 90 psi. Any help would be greatly appreciated. Thanks