If it makes you feel any better I have the same issue with my 6700. I found that I needed to raise the back of the foot by putting a thickly folded square of fabric under it while I sewed. With or without the walking foot. This is Kinda like a hump jumper you use for denim seams. My 6600 never had that problem so needless to say it made me less than happy to have a machine that costs twice as much not live up to the reputation of the brand.