I found the same thing happened when I lost the original foot and used the spare in my accessories kit (which came with the machine) the only way I could stop this from happening was to sew without the foot pressed down (not ideal) so I came to the conclusion that there was a problem with the foot and stitch combination I was using. I am new to sewing and as you can tell far from an expert in these matters - my next step was going to be to buy a new all purpose foot and see if this fixes the problem.
Gill
November 2005