Why upper thread breaks？

Upper thread breaks

Cause:
1. The machine is not threaded correctly.
2. The thread tension is too tight.
3. The thread is too thick for the needle.
4. The needle is not inserted correctly.
5. The thread is wound around the spool holder pin.
6. The needle is damaged.

Correction:
1. Rethread the machine.
2. Reduce the thread tension. (lower number)
3. Select a larger needle.
4. Remove and reinsert the needle. (À at side towards the back)
5. Remove the spool and wind thread onto spool.
6. Replace the needle.