am having difficulty piecing a perfect 1/4 inch seam with my 1/4 inch foot ..when I use my walking foot to piece, I get an even piecing due to the dual feed, but there is a little bit that sticks out from the bottom piece of the seam , when I use my 1/4 inch foot and I have to try and even it out, frustrating,, hope I am making this clear..I saw a demo on the computer site using a different type foot to piece on the bernina, can anyone help me.. thank you, yetta