Magnets will mess up anything computerized. It also messes up the black strips on credit cards and stuff. I had a Kenmore machine, ca. 1984. that got the bobbin body magnetized somehow, according to the repair man, and it would not sew. So, I guess it can happen, however, in my case. I discovered that the needle bar was jammed on a heavy seam. It shortened the stroke of the needle and would not loop with the bobbin. After the $55 repair bill, I fixed it myself for free! :evil: