The thread could be jamming due to several reasons.

• The upper thread could be tangled. Remove the thread completely from the machine.
  The correct size spool cap should be used for the size of the thread spool.
  Re-thread the machine according to the directions in the manual.

One Point Advice  Place a spool of thread on a spool pin

One Point Advice  Upper threading

• Remove the bobbin and make sure the bobbin is threaded properly in the shuttle race.
  Remove any loose threads or lint in the shuttle race.

One Point Advice  When thread got tangled

One Point Advice  Lower(bobbin) threading

• The tension could be too tight or too loose.
  Set the tension to the best thread tension setting or adjust the tension manually.
  
  
• Needle and thread are incorrect. Be sure to use the correct thread and embroidery needle(s).