Originally Posted by
RotaryQueen
In addition to the excellent suggestions above, are you holding the top and bottom threads to start each square? My Kenny will "suck" the top thread down into the seam and several stitches in I get a jam such as you describe, including three threads in the bobbin shuttle. If I remember to hold, and put slight tension, on the threads to keep them out of the needle path he sews very well.
Silly question time.
Are you using the right bobbin?
Try a regular needle instead of a ball point?
Are you using a good thread?
All of these have tripped me up at different times, resulting in thread knots.