I think that I am done working on this compressor. I have reinstalled the electric unloader valve. I had some trouble with it, since due to
58 years of use, the valve was packed with crud and leaked air from tank when the valve was off. So I had to take it apart and soak the parts in gasoline for a few hours and wash them.To make the unloader work, I had to replace the old diaphragms. Due to their age, they were as brittle as saltine cookies and obviously had to be thrown away.
The unloader works by opening intake valves. Also, when it unloads, it dumps contents of the high pressure cylinder to atmosphere. That was obnoxiously loud when the compressor unloads when full. To mitigate this, I bought a 1/8" NPT muffler and attached it to the opening with a 1/4" OD copper tube and compression fitting.
I also put all cables in conduits or use armored cables where necessary.
For air hose, I installed a big hose reel, which I now know is much better than hanging hose on a hanger (because it does not kink).
Pictures of all of this, as well as the sand blaster, are here: