Debbiemarie I responded to your other post before I saw this one. I drive a bernina too and I would highly suggest you purchase the #37 foot if one did not come with your machine. The edge of the foot is 1/4" and the inside of the foot edge is 1/8" from both sides. It's a perfect foot and I use mine more than any other. How long have you had your machine? I think all bernina dealers would look at your machine and help you with your issue.
Also I would suggest a straight stitch plate if you ever need to spurge on a bernina accessory ;-) it's great for piecing.