Rethread your machine, check to see if you bobbin is wound correctly, then make a sample sandwich out of the same fabric you are trying to FMQ. Adjust your top tension one notch, or number and check your stitchs. Do this till your stitchs are balenced. Try loosening the tension first. I have to adjust my tension for every quilt I work on. Don't know why. Work on the sample till you're happy with the stitchs. If you get frustrated, walk away for awhile.