This is pretty obvious, but..... I got my 6600 to leave at the vacation home on the lake. I got it in September and that year we didnt go there in the winter. I must've changed the needle plate to the straight stitch one and forgot that it came with 2 plates. I was trying to do a zigzag or decorative stitch and it would stitch a couple and then stop and stitch in place. I called the shop and she even asked me about the plate. I ended up driving 30 miles to take it in and sure enough she sat down, looked at it and said you have the wrong plate on here! I was so embarrassed! I felt stupid. Then I had to find the plate- it doesn't fit into the accesory box- ended up being in between folds of fabric. Changed the plate and low and behold- it was fine. I hope that your problem is an inexpensive fix. It's really a great machine and I truly love it.