If you are using the horizontal spool, be certain that the cap keeps the thread from winding on spool. I have had the machine for a little less than a year and the only time I had trouble with the thread was when I used the thread stand. I had threaded it through both loops and as a result, it put too much resistance on the thread. If all of the advice doesn't solve the problem, phone your dealer or the Juki company. They are great.