The best information I have found is:
http://www.tfsr.org/pub/technical_in...echanism_2.pdf
I could not explain how the tensions work any better in a hundred years. That manual is worth it's weight in gold.
The first time you do one have someone around that is supportive. Take some pictures as you go. Keep track of how things come off - they go back in the same order and in the same direction.
My first spartan looked like it had never been used. I thought I found a cheap machine for once that didn't need any work. Then I tried to sew on it. The tension spring wasn't engaged right. That manual told how to get it in the right place - it was an easy fix. If you can follow a pattern you can do a tension.
The finish on that little 99 looks about like my FW did before I cleaned it off. Glenn has a tutorial on refinishing or you can pm Glenn to get the info.
http://www.quiltingboard.com/vintage...3881-3299.html or window #32981 for the start March 31,2012 lots of fun on there.