paint compressor question
 

Hello everybody.I have a question for the old timers re. the Miller 3100 paint compressor..I have used this compressor for years an it has served me well.In order to use an airbrush like a Badger you have to get a model 9090 relief valve.I have one an it did not adjust.I opened it up an all it had inside was a small spring.I guess there is a plunger or something that is missing.I know this a stretch but if anybody has one of these could they unscrew the adjustment knob and tell me what is inside:better still,send a picture.
Thanks
Bob