Originally Posted by writerwomen

take a piece of thread and knot it several times and trun it back and forth in the tension discs to clean it. As you thread be sure you're in between the right disks- should be the two closest to the machine. Tighten your tension down all the way and back it off until you get a good stitch. Also can totally loosen it and work up. The pring can get stuck so take the disks off and check to make sure it is clean and fully extended ( in worst case may need a new spring. The thread you are using if varied in any way from what your machine is used to can throw it off. Sometimes in rare cases you need to adjust the bobbin tension. Look on lone for sewing machine trouble shooting tips- there are some good ones out there