We paid $7.00 for our 4622A at a yard sale. It needed one part that cost about $10.00. Then it needed lubed and now it does excellent stretch stitches. No external cams, just internal ones and it's simple to use. That is the only reason it's still here and hasn't been rehomed.
Have you removed all the little knobs at the top of the front if they pass through the top piece?
Joe