Hi Libbi, I had the same problem with my BSR (for the 820) and I took in into the dealer to try it on one of their machines. It was skipping stitches horribly and I tried everything. It wasn't working on their machine either. Turns out that sometimes the spring is weak and needs replacing, or the BSR needs to be calibrated with your machine. I found that it skipped really bad when I was working on a quilt that was sprayed basted with 505. There is an issue with this, as I've joined other Bernina forums and this has been discussed.
So, I know there may be some user error, but chances are you could have a bad BSR. I'd take it in to the dealer and check it on their machine if you keep having problems. And another dealer told me using titanium needles helps if you are spray basting, because the glue doesn't adhere to those needles. I'm a new Bernina 820 owner, and I'm learning all of the nuances with this machine. I do love it none the less, but there is a learning curve.
Good luck. -sheila