Damage to the Rotary Hook
If there is any damage to the Rotary Hook, the thread will break on every needle. You will need to visually examine the hook for any damage.
1. Turn the Rotary Hook so that you can see the top part of the hook. If you have any damage, it will look like the Figure 12.
2. If there is damage to the Rotary Hook, you will need to polish it with crocus cloth (you can find this at any hardware store).
3. First, you will need to remove the rotary hook support bar (black bar just under the needle plate). There will be 2 small flat head screws to remove the bar. This will provide you with more space to polish the hook.
4. Next, polish the damaged area of the rotary hook. You can do this while the Hook is still on the machine. The goal is create a smooth surface, so the thread does not catch on the damaged hook and break.