Originally Posted by
Bennett
On the 201, it should be the same as other Singers of the period. I've found this link helpful for troubleshooting, taking apart, and putting back together the tension on 66s and 99s, both old style and newer style with the number dial.
TFSR manual.
Hope it helps!
This manual link has so-o-o much information on not just the tensioners but also just about everything else that you need to know about antique/vintage Singer sewing machines. I've just solved 2 problems that I'm having, with two separate machines, by reading through the different sections of that link.