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◎ Needle broken  |
| Might be： |
1. The position of the needle guard is incorrect.
2. Incorrect timing cooperation between the feed dog and the rear roller.
3. Incorrect timing positional relationship of the needle and looper.
4. The pressure of the thread tension adjusting knob is too strong.
5. Incorrect timing of the thread control cam, HD07.
6. The high and low positions of the feed dog are incorrect.
7. The needle is assembled incorrectly.
8. The needle rubs against the presser foot.
9. The needle is too thick or poor quality. |
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◎ Skipped stitches |
| Might be： |
1. The position of the needle guard is incorrect.
2. Incorrect timing positional relationship of the needle and looper.
3. Incorrect timing of the thread control cam, HD07.
4. Incorrect timing cooperation between the feed dog and the rear roller.
5. Incorrect threading.
6. Inappropriate adjustments of the thread guiding system, VK13, VK18, VK11, and HK18.
7. The needle is assembled incorrectly or assembled in wrong position.
8. The pressure adjustment of the thread tension control knob is improper.
9. The pressure adjustment of the presser foot is improper.
10. The needle is bent or has burrs.
11. The quality of the needle is poor.
12. The high and low positions of the needle bar are incorrect.
13. The looper set and the connecting rod, HE27, HE37, are worn. As a result, the looper is loose in left and right directions.
14. The looper set HE07 is worn and this causes the looper loose in front and rear directions. |
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◎ Thread broken |
| Might be： |
1. The positions of the needle and the needle guard are incorrect.
2. Incorrect timing positional relationship of the needle and looper.
3. The pressure of the thread tension adjusting knob is too strong.
4. The timing adjustment of the thread control cam is incorrect.
5. Inappropriate adjustments of the thread guiding system, VK13, VK18, VK11, and HK18.
6. Incorrect threading.
7.The needle is bent or has burrs.
8. The thread quality is poor or the thread is uneven.
9. The looper is worn or has burrs.
10. The sewing material is not fed completely under the presser foot while sewing.
11 Incorrect positional interrelation between the needle and the needle plate hole. |
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◎ Sewing is not smoothly. |
| Might be： |
1. Incorrect position of the feed dog.
2. The pressure adjustment of the presser foot is incorrect.
3. Incorrect timing cooperation between the feed dog and the rear roller.
4. The clearance between the upper and the lower roller is incorrect or the two rollers are not parallel to each other.
5. The feed dog is worn or does not stay horizontally.
6. The pressure adjustment of the thread tension control knob is incorrect.
7. The pressure adjustment of the rear roller is incorrect.
8. The rear roller doesn't function well.
9. The thread tension control cam doesn't control well.
10. Incorrect position of the folder.
11. The torsion of the rear roller is too weak and causes the uneven stitch lengths. |
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◎ Noise |
| Might be： |
1. The lubricating is not enough.
2. The part VF02 is loose because of being worn out after a long term usage.
3. The part HE14 is loose because of being worn out after a long term usage.
4. The part VCL12 is loose because of being worn out after a long term usage.
5. The part HA09 doesn't connect with the machine well.
6. The part KB05 is fallen off.
7. The machine is not adjusted well.
8. The needle bar is loose in up and down directions because the parts VF21 and VF24 are worn out after a long term usage. |
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