I also have the 6600 and it came with the AccuFeed 1/4" foot and couple of others as a promotional deal. I don't like the foot for piecing either. Clunky describes it perfectly. I use the regular 1/4" foot with the quide. I think the AccuFeed foot is designed to keep the fabric and batting feeding evenly. It works better with several thicknesses of fabric. About the only thing the AccuFeed 1/4" foot is good for is sewing binding on the quilt before you turn it and handstitch. If you just purchased the foot, I would say take it back and tell the dealer that it doesn't work for you.