1. Sewing machine vibration failure
        The machine must be stable and the machine must be stable. The rotary hook structure is the key to the level of noise and vibration of modern sewing machines. The screws must be tightened firmly when installing the machine. .
       When using the machine, do not put all the weight of the person on the platen to prevent deformation of the platen.
2. Trouble in the operation of the sewing machine
　　 The machine head is turning sluggishly
　　Analysis: The wrong lubricating oil was added, especially vegetable oil; there was too much dirt in the shuttle bed; the connecting rod screw and the conical screw were installed too tightly. Treatment method: After washing with kerosene, refill the sewing machine oil; clean the shuttle bed; loosen the screws to ensure the clearance.
　　 When sending, half circle is stagnant, half circle is lightly slippery or there is a stagnation point for each circle
　　Analysis: The inner wheel of the shuttle bed has a threaded end. When it is running, it is not only half-turn but also accompanied by severe jitter and noise; the position of the feed dog is too high or dirt accumulates in the tooth gap, which makes the feed dog collide with the needle plate when it rises. Treatment method: clean the shuttle bed and add a little sewing machine oil; clean or lower the feed dog; replace or straighten the needle bar.
　　 The machine head is stuck and cannot move
　　Analysis: the feed dog is too far forward or too far back, and it touches the needle plate; the needle bar is installed too high, and the needle clamp touches the casing. Treatment method: adjust the position of the feed dog, re-align the needle, and adjust the height of the needle bar.
　　The noise comes from the needle mechanism
　　Analysis: The wear and tear of the needle bar, needle bar cover, small connecting rod, etc. are too large; the small connecting rod screw and the needle bar crank screw are loose. Solution: Replace the new needle bar, needle bar cover, small connecting rod and other accessories; re-tighten the small connecting rod screw and the needle bar crank screw.
　　The noise comes from the feeding mechanism
　　Analysis: the large pointed cone screw is worn or loosened, the feeding tooth touches the needle plate, and the stitch length adjustment mechanism is loose. Processing method: grinding or re-adjusting the large-pointed cone screw, re-adjusting the needle plate of the feeder, re-adjusting or tightening the screw of the needle pitch adjustment mechanism.
　　The noise comes from the shuttle mechanism
　　Analysis: The wear of the shuttle and the shuttle bed causes the gap to be large, and the gap between the shuttle and the shuttle holder is too large to cause shock. Treatment method: replace the new shuttle and shuttle bed, etc., adjust the distance or replace the new shuttle and shuttle holder.
　　 general noise
　　Analysis: the upper shaft, lower shaft and sleeve are worn out, causing the upper and lower shafts to move; or the machine is out of oil. Treatment method: replace the upper shaft, lower shaft and shaft sleeve with new ones, or adjust the gap between the upper and lower shaft planes, pay attention to maintenance, and add lubricating oil on time.

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