Anyone maybe have an idea what is going on with a/this Shoebox compressor;

3000psi model, the lock ring for the rod/spring actuator to disengage the motor when set pressure is reached has been set for 3300psi (i.e. as far out on the rod as it will reach)- and it is still sitting there, but compressor/motor is cutting out at 2000psi.

Last time it was used a few weeks ago- it was working A-Ok at 3300psi and has only sat since yesterday when this developed.

Anyone have any knowledge or idea why this would occur? (compressor is not exactly "heavily used")