Of course the tension parts got all jumbled up on the magnet so the next best is to look in the TFSR manual:
http://www.tfsr.org/publications/tec...achine_manual/
You can look there for info on tensions.
Tammi has been working on some info on tensions. Watch for it in a few days. She's done a very nice video on the 201 tension. I sent her photos from this machine to add to her info. There are more than one tension type for the Singer 99. The 66 is just the basic older style with no numbers.
Muv also has a lot of information on her videos and in her blog:
http://www.quiltingboard.com/vintage...v-t167789.html