1. The upper thread may not be properly set and that makes the thread break.
A : Check the manual for a correct installation instruction.
2. Upper tension may be set too strong
A : Please adjust upper tension by tension dial and find a proper value for it.
3. It may be caused by a bending needle or a damaged one.
A : Please replace a new needle
4. The needle may not be correctly set.
A：Please check and manual and re-install the needle (note: flat part of the shank must be set in rear side direction)
5. In the beginning of sewing, the upper and lower thread aren’t put in the right place, they need to be under the presser foot.
A : Check the threads position and be sure to put them under the presser foot in the beginning of sewing
6. The selected thread is too thick or too thin compare to the needle size.
A : Choose the correct thread for your sewing application