Thanks! I have a better understanding of them now. The relay valve was what had me puzzled as to its function. It seems mine is leaking at what appears to be a allen hex head plug which is baffling. Maybe it is not a plug and is open at the bottom.
It's all hard to tell until I get it cleaned up.
I did replace some of the copper with nylon a couple of years ago.
It doesn't get much use these days as the old 366 is pretty tired and worn out. I try to start and move it around every so often to keep the rats confused. Yesterday I noticed the air leaking.
Time to address the brakes.
