If skipped stitches occur frequently, the synchronization between the needle and the rotary hook should be verified. When the needle bar reaches its lowest position, the hook point should be 2.5–3 mm away from the needle centerline, and the hooking action should be completed when the needle eye rises to 1.5–2 mm above the needle plate surface.
For intermittent skipped stitches when sewing thick materials, try raising the needle bar height by 0.3–0.5 mm to enhance loop stability, and replace the needle plate with a dedicated heavy-material type featuring a U-shaped groove. When handling elastic knitted fabrics, using a differential feed mechanism in combination with reducing the presser foot pressure to below 1.5 N can effectively minimize stitch deformation caused by fabric stretching.
It should also be noted that accumulated dirt on the take-up mechanism due to long-term lack of cleaning, or worn feed dogs, can lead to irregular skipped stitches. Regular disassembly, inspection, and application of specialized lubricating grease are therefore necessary.