I bought a Kenmore several months ago. Mom liked it so well, she bought the same model. However, we were both having intermittent problems with excess thread on the bottom, especially when quilting. We knew it was a tension problem, but couldn't figure out how to fix it. I finally did a search on the internet and found this tip. That was a couple weeks ago and, so far, we haven't had the problem. Apparently, everything was fine if we "accidentally" threaded with the foot up, but had trouble when we "accidentally" threaded with the foot down.
We are now both back to LOVING our Kenmores!