Clean out the fuzz in the bobbin case! I sew a lot of fleece blankets (double thickness) and it will pick up fuzz quickly. I use an 80 needle, walking foot( let it pull fabric thru , that is what it is for) and a zig zag is what i use as it gives stretch on the blanket and length the stitch length slightly! Clean out the fuzz in the bobbin case if most important, try that first. Good luck. P.S. I make fleece blankets for homeless people and I always have to clean out the bobbin area!!!!