Lisa
First check your book on tension control. I have mine set between 4-5, I meander and stipple all the time. Make sure there is no fuz from previous quilting projects in your bobbin casing, Don't fiddle with the screw, untill the last resort. Have you changed your needle? I use a needle for heavy fabric, such as denim. Sometimes it is the thread it's self, Also could be the thread in the bobbin not wound correctley. Some thread just dosen't do well. I have problems with rayon thread, In your manuel, there is usually a section for trouble shooting, read through that. If none of this works then ask Patrice......