You can't beat the older machines that just sew straight stitching for piecing because the feeddogs only go one direction. When you have a machine that can zigzag then here is where things change. The pressure on the needle is a good suggestion. Also try moving your needle to the right and using a wider foot that will help hold the fabric in line. When moving the needle to the right measure where your quarter inch is and use tape or whatever to mark it and by using a wider foot than the quarter inch foot will help control this issue.
Good Luck
Suzy