SCM support's response was they didn't know what size or type of plug came with the machine (I had to send 2 of them the pics of the fitting) and to just replace back to the hose or pick something close and thread it in. Then they looked online and sent me the info for an adapter that I then bought; it didn't fit. The new fitting was .39" and the old was .37". I'm going to move onto replacing back 4 more parts into the machine to get back to the hose.

Hey SCM, if you're going to supply a non-standard air quick disconnect, send both parts. At a minimum, list the exact specs of what's needed in the parts manual (more than "fitting") or install instructions ("...next, hook up the air"). Oh, and while you're at it, actually install the electrical power connection box on the outside of the machine like your drawings show (and every other SCM machine I've ever owned has) instead of a blank plate and having me drill a cord grip hole through the 1/4" steel plate and route my power wires through the inside of your machine.