I dont have that machine but the tension adjustment should be about the same on any machine. Have you changed weights of thread or anything else? You might have to end up adjusting both top and bottom tension. Here is a link on how to check and adjust bobbin tension
http://www.youtube.com/watch?v=0bXrK...eature=related
Be sure and clean the bobbin area really well and check the bobbin case itsself, lint can get under the little clips or springs and really mess things up!!!!