The looping bobbin thread is usually caused by the upper threading of the sewing machine. These pointers should have you sewing again in no time. If bobbin thread is smoothly and evenly wound on the bobbin, the bobbin is not the culprit.
- Always thread the sewing machine with the presser foot up. As long as the presser foot is up, the thread can seat properly. When the presser foot is down, the tension is engaged and it will not allow the thread to seat properly.
- Re-thread the sewing machine making sure the thread is passing through every thread guide on its way to the sewing machine needle. Your sewing machine manual is the best guide to how to thread your particular sewing machine.
- If you're still having, loopy bobbin thread, change the sewing machine needle. Be sure you are using the proper sewing machine needle for the fabric you are sewing and the job at hand. Everything About Sewing Machine Needles