Are your needles breaking in your fabric? Are they hitting the stitch plate when going down? Are they actually hitting the walking foot on the way down? I had a problem for awhile where my needle placement changed of its own volition and wasn't going into the hole properly. After turning it off and on numerous times it fixed itself. Two other things that I'm sure you've thought of that are still worth mentioning, make sure your needle is all the way up where it belongs and screwed in tightly. Also, when you are sewing make sure the fabric is being fed by the machine and that you aren't pulling the fabric at all - that can cause enough tension to break the needles. I hope you can get your problem resolved soon without too much angst...there is nothing worse than a mystery problem that you have no idea how to solve. As toolazy said, maybe there is a problem with the walking foot and needs to be replaced. please keep us updated, we'd love to know what the problem was and how it was resolved!