Ok to start off I have a 1966 Chicago pneumatics tow behind model- 77103 size- 85 RG-1. I need help with 2 different things to make the one thing work. So it starts fine builds pressure fast. It won't idle itself down when air isn't needed just keeps building up air. "So I'm guessing unloader valve?" And the next thing I need some help with the linkage or how they are set up I can't seem to figure It out I'm not sure why. "And I'm not sure if I'm missing a piece somewhere or not like a spring" also to add not sure if this makes any difference or would give me my problems, but the air compressor is hooked up to a 500 gallon air tank for storage. Hopefully you can help me ive spent countless hours looking for manuals and just information and I find hardly anything