I would guess your thread is catching on something on your machine. My Brother feeds off sideways, and if I am using thread that has a small nick in the edge of the spool for anchoring the thread after you have finished using it, the thread will catch on it and gather and/or break. I use mostly cones...some only 1100 meters and some 5000 meters and because of this I now use a free standing or machine mounted thread holder and no longer have the problem.