This is where I will try and help you out with links to people who know stuff about these old machines. Also you will find my posts on cleaning and repairing vintage sewing machines here.
For Sewing Machine Parts:
Shop owner is Jenny and she sells some hard to find parts as well as after market parts for Vintage Sewing Machines, but particularly for Singers
This shop is great and they are in Georgia, they sell parts for newer and older machines
This is a reliable EBay shop if you like using EBay. They ship fast and are very good with lots of parts for newer and older machines.
April has a great deal of knowledge about Singer 221's (Featherweights) and her shop is dedicated to it. She only sells parts for that machine.
For Sewing Machine Repair troubleshooting and other information:
Let me just say, this chick is awe inspiring when it comes to how great a job she does with photographing the repairs she does, her advice, and just all of the amazing info on her blog. L-O-V-E her site and it has helped me tremendously, especially when I started this crazy little hobby of mine.
This site is a great resource, for many things including free manuals. There is a collectors corner, and some great photos of old machines.
I just kind of like his name, but he also has some resources on repair etc.