1. The needle tip is not sharp, bent willies. Replacement needle.
2. The needle and the Rotary hook tip clearance is too large. Readjust the relativeposition of the hook.
3. Hook nose blunt or slight defect. Grinding spindle cusp and polishing.
4. Embroider the tension is too loose. Taut fabric with embroidery.
5. The embroidery presser foot spring pressure is not enough or are damaged replace the embroidery presser foot spring.
6. Embroidery thread and needle not according to the thickness of embroidery thread select the thickness of the thickness of the needle types.