I have a 1600P also and have same problem a lot... Every time I think I have it conquered, it starts again. I have tried all the suggestions. Eventually something clicks (with the machine, not me) and it goes great for a while. I "think" one thing that seems to help is slightly looser tension on the fabric in the frame and keeping the fabric level with the sewing machine bed. But sure as I said that, it won't work for me next time. So good luck! Even with all the aggravation, I still prefer using the frame over trying to sandwich a quilt and do it the "normal" way.