18aa367c_ooting_Sewing_Machine_Problems__Symptom
[Root Cause] Thread has not been pulled into thread sensor guide. Threading is not correct. Bobbin case has been threaded wrong. Spool cap is wrong size for thread spool. [Corrective Action] Fully pull thread into thread sensor guide. Correct threading. Correctly thread bobbin case. Replace the cap with correct size. [Symptom] 
Stitches are not formed properly.
Troubleshooting Sewing Machine Problems
Symptom