1/4" Foot
I've had my 6600 for several years now. I always test my 1/4" seam on every change of a foot. An index card with lines have exactly 1/4" spaces. I carefully cut off the bottom line as it is shorter, turn the card over to the blank side and sew a seam. If I stayed on the line it is an exact 1/4". If I want a scant 1/4" the card helps to check it out also. I set of 100 cards is less than $1.00 at my local drugstore in the school supply section.
I moved the needle over and I get the 1/4' seam.
Has anyone else had this problem? I wonder if I got a bad foot.