My first guess would be that there is gunk under the bobbin case causing it to not spin freely creating the nests. I would remove the bobbin case and clean under it. When I first get an old machine, I open it all up and clean everything with kerosene and then oil it all, although I understand sewing machine oil only is the favored method here.
The bobbin case on the 201 might give you trouble the first time you do it (I had more trouble getting it back together than taking it out). Here's a good tutorial by Rain:
http://vssmb.blogspot.com/2011/07/ho...bbin-case.html
You can follow his links to removal of the hook and then reinstallation. I didn't remove my hook, as it didn't look that bad but if yours looks like it's packed with lint you might want to do that.
You can also try cleaning the tension assembly with some dental floss.
Good luck.