Depending on your machine, you might try switching the direction of the thread spool pin. Some machines are just finicky. Aurifil, like Guterman, is a cross wound thread, which means it "should" sit upright on the spool pin. However, for some reason on my new machine, Aurifil always breaks when I set it upright so I use it on the sideways spool pin. Strangely, my old machine only had an upright post for the thread & I had no issues with that.