I'm tryng to clean up and get to grand working order an old 6020. I can't get the A cam in the back of the machine to come out. From what I can tell, it just pulls straight out, right? Also, the stitch selector dial (top left) and the stitch width dial (bottom right) won't rotate. Am I doing something wrong? Please help me before I pull my hair out. :?

To remove the cam, line up the white dot on the stitch selector dial to the black dot on the machine body. It should come out with a gentle tug. These dots also need to be lined up to insert a cam.

Width dial - is the front (light) part pulled out? If the front part is pulled out, the dial won't rotate. Part of the buttonhole making process has to do with this dial being pulled out.

Stitch selector dial - Hmmmmm - I don't have an answer for this one. I'll try to figure this one out.

There's a vintage Viking group on Yahoo. They can be very helpful with problems like these.