Red Pro Air 2

Hi Cas, I am a newby and inherited this compressor it has a couple of problems. 1/ it very slowly leaks (check valve?) 2/ the manually operated valve to the outside line (which has a second pressure gauge attached to show pressure I am sending to the outside) does not work properly. My question for 2/ is what is the valve called part number and where can I get one? Thanks in advance. Leo