First, don't mess with the tension. Sew a sandwich with a straight stitch. Tension OK? THEN DON'T CHANGE YOUR TENSION, IT IS FINE. Eyelashes are formed when your hands are moving too fast for your machine to catch up with that motion. You can either slow your hand movement or speed up your machine. The Blue dot bobbin works great. I have two 6600's one for home, one for cabin. Love this machine.