The small thread clamp controls the length of the thread. If the pressure is too high, the thread will be too short and the thread will come out of the needle hole during the second sewing. : {; g9 r/ m" A! i( P; S. When the thread-cutting electromagnet is working, pay attention to see if the large thread clamp springs open. If it does not spring open, push the large thread clamp inward a little less. Toyama Machine Repair Club Sewing Machine Forum Sewing Equipment Forum Sewing Machine Repair Sewing Machine Video: M# q/ C. z! l# x: A4 R; s3. Pay attention to check whether the position of the tangent cam is correct. There is a high possibility of problems in this place 4. . Check whether the handwheel is installed correctly and whether the sensor at the handwheel is installed correctly. N: D; _# i& H5. If it is a Brother computer flat car, or an imitation Brother computer flat car, pay attention to whether it is a moving knife. The installation position is too forward, which means the thread is cut too early. 6. If it is a heavy-duty machine, or a machine imitating a heavy-duty machine, pay attention to whether the fixed knife is installed at the far left. Pay attention to whether the thread stopper has too much pressure. # L2 u W+ ~- F: N) O( V3 i8. If it is an imitation brother computer car, pay attention to whether the left side of the moving knife is worn. In some of these machines, the tangential precession of the moving knife is prone to not resetting. If the moving knife If it gets stuck, the needle will collide with the movable knife when starting the needle for the second time, which will damage the needle and the left side of the movable knife. If there are scars on the left side of the movable knife, the thread will not enter the movable knife smoothly during thread trimming. The gap in the knife causes the upper thread to be too short. The thread end will fall out of the needle eye when the needle is lifted for the second time.