- Bent needle, misaligned needle tip (usually caused by skipping stitches on stretchy fabric; replace with size 11 or 9 needle). It is recommended to use Japanese needles; a pack of 10 needles costs around 20,000 VND or more.
- Incorrect straight stitch selection (one type of straight stitch for thin fabric, another type for thick fabric).

- Bobbin case misalignment (take the machine to a store for inspection).

- Incorrect needle installation.

Note: Needles from size 9 to 11 (for thin fabrics) should use a straight stitch positioned on the left side of the presser foot. Needles from size 14 and above (for thick fabrics) should use a straight stitch positioned in the center of the presser foot. If using the left-positioned straight stitch (meant for thin fabrics) with a thick needle, the needle may break or cause bobbin misalignment.

Needle size 9: Use if size 11 needle skips stitches.

- Needle size 11: Suitable for stretchy fabric, chiffon, kate fabric, and dress pants (thin fabrics).
- Needle size 14 and above: Suitable for khaki and denim (depending on the thickness of the denim, choose size 14, 16, or 18). However, to maintain the machine’s longevity, avoid sewing excessively thick fabrics continuously.