1. The sewing machine head rotates slowly.

Product reason: Adding the wrong lubricant, especially the vegetable oil. There is too much dirt in the shuttle bed, the connecting rod screws and the conical screws are too tight.

Treatment method: After rinsing with kerosene, refill the sewing machine oil. Clean the shuttle and loosen the screws to ensure a certain clearance.

2. When sending, half a circle is sluggish, half a circle is slippery or there is a stagnation point per revolution.

Product reason: The inner ring of the shuttle bed is not only half-slung but also accompanied by severe jitter and noise. The position of the feed dog is too high or dirt accumulates in the tooth gap, causing the feed dog to collide with the needle plate when it rises.

Treatment: Clean the shuttle and add a little sewing oil. Clean or lower the feed dog. Replace or straighten the needle bar.

3. The sewing machine head is stuck and cannot move.

Product reason: The position of the feed dog is too far forward or too close to the needle plate. The needle bar is installed too high and the needle clamps against the casing.

Treatment method: adjust the position of the feed dog, re-align the needle, and adjust the height of the needle bar.