for Pro Source compressor Air Compressor 1110c060902037348 I followed the instructions, running the compressor for 20 minutes w/o the air drain **** and then putting it back on. After turning the compressor on, I turned the regulator knob fully counterclockwise, expecting the compressor to build maximum preset pressure and shut off. However, it just kept running. The tank and outline gauges remained at 0. What do I need to do to get it to work?