Adjust the needle guard:
The machine pulley to align the tip of the rotary hook (1) with the center of the needle, and then loosen the bolt (3) and turn the needle guard adjusting shaft (4) to adjust so that the needle guard (2) is touching the needle.
If it crosses the needle more than necessary, it will place a load on the needle, or it may cause poor thread tension. Furthermore, if it does not cross at all, the tip of the rotary hook (1) will interfere with the needle and skipped stitches may occur.
Adjusting the needle clearance: