Hello, my name is Peacock and I am addicted to sewing machines. LOL! Is there a 12-step program for this?

Sorry . . . that's just what popped into my mind when I wrote "Rehab." What I really mean is rehabbing the machines. I keep seeing these cool vintage machines at yard sales, rummage sales and because I do truly love sewing, I want to snap them up and fix them up, get them running well, polish them and SELL them.
I've bought 4 of them within the last month - three vintage Singers including a treadle (but I'm keeping that one) and a vintage Viking. I'm sure they're worth a lot more than I paid, which was nearly nothing. But my question is this -- how does one learn how to work on sewing machines?
Hubby is quite mechanically adept, but this is my project, and I am not. But I could learn. I just don't know how to go about learning. Ideas? Books? Videos? Thanks!