Here's something else to note that was in my Qnique15 Pro instruction book, but not in my 21 Pro: Watch to make sure that the thread goes up and down the bobbin hub as it winds - if it doesn't, you need to adjust the tension. My Long Arm machine book gives this instruction: If the thread bunches at the bottom, reduce tension on tension disc. If thread bunches at the top, increase tension on tension disc.