My new, regular quilting foot came in the mail today. I cleaned the machine well, oiled, put in a new needle and rethreaded everything. I quilted for a good while and didn't get any nests or skips. I'm actually not totally surprised that the skipping is gone with the use of a regular FMQ foot. I'm convinced there is a design flaw with the BSR and I'm far from the only person who's had issues with it. It didn't work right with my 440 and doesn't work with this 820. As for the thread nests on the back, who knows. So many of you posted about simple fixes like rethreading and needle changes. I guessed after a few days of changing things I finally changed whatever was causing the problem. Course I'm not holding my breath thinking all will stay well. This is a picky, temperamental machine and it seems to have very narrow tolerances.
Thanks to everyone for your help and support!