Your practice stitching is coming out fine? That sure is a mystery. Is the problem that the stitches are uneven on the backside of your quilt...or are there little "nests" or loose loops of thread when you look? Every machine seems to be different, but with mine (Janome) both the tension, feed dogs and presser foot have to be adjusted to darning. That seems to solve the balls and loops of thread problem. If it's the stitches that're uneven, that's practice, practice, practice! I always have to remember to relax and watch my machine speed. Hope this helps :D