If you were saying the seam seems to veer off at the end, the way to keep a perfectly straight seam at the end is to put your finger against the left edge of the foot and the seam will stay straight. A Command refill strip makes the perfect seam guide, it comes right off with no residue to deal with. It took me a long time to get the 1/4" seam consistent but it is very important when following a pattern.