The center removable part of the throat-plate on my machine is just slightly higher than the rest of the machine bed and I noticed it often caught the edge of the seam allowances and was flipping them to the other side when sewing. So I put a couple of strips of blue painters tape on the front edge of the throat-plate to make it smooth from the machine bed to the needle area. This has helped me keep my seam allowances in the right direction.