Broken needle
(1) The needle is too thin and the needle is bent.
(2) The stitches are too tight.
(3) The gap between the needle and the looper and the amount of back insertion between the needle and the looper.
(4) Clearance between the needle and the needle plate, presser foot, etc.
Solution
(1) Replace the needle with a thick needle.
(2) Properly loosen the sutures.
(3) Readjust the gap between the needle and the looper.
(4) Adjust the clearance between the needle and the needle plate, presser foot, etc.
