Victory! The big nasty constant leak is fixed. It took an o-ring inside one of the unloader actuators and some creativity with bike inner tubes. More permanent diaphragms will be made Wednesday night since the current setup is a band-aid fix over the old crappy ones.
I also made a wiki page with info on the machine and project progress: http://tcmaker.org/wiki/doku.php?id=fac ... compressor
I'd like to work on plumbing the shop, and will put in a strong vote for PEX. Where can you buy PEX tubing and fittings for a reasonable rate? Can you just get that stuff at Home Depot, etc. these days? And does anyone here own a PEX crimper, or di I need to make one?