Originally Posted by ckcowl
you may need to clean your machine, take the bobbin out and clean that area well, if there is lint built up in there it can cause tension problems...i would clean the machine, put in a new needle (making sure it is a universal or sharp/not a ball point) make sure the needle is inserted correctly and try again. you may not have to mess with the tension, if it 's an issue with lint built up.
Also try rethreading the machine. Sometimes the thread can jump out of its assigned place without you realizing it.