Singer 321C Instruction Manual And Parts List page 22

Problems
1. Wrong threading.
2. Wrong installation of thread stand.
3. Wrong setting of lower knfe.
4. Knives does not cut perfectly.
Uneven Stitches
5. Thread guide or tension disc with burrs.
6. Needle point damaged.
7. Inadequate height of feed dog.
8. Inadequate thread tension.
1. Thread tension is too strong.
2. Inadequate pressure on presser foot.
3. Inadequate height of feed dog.
Puckering
4. Knives does not cut perfectly.
5. Differential feed is not correct.
6. Needle is too thick.
1. Incorrect presser foot.
2. Inadequate synchronism of lopper cam.
3. Chain stitch looper installed wrongly.
4. Wrong passage of thread.
Poor
chain-off stitches
5. Thread tension inadequate.
6. Wrong relation of needle with looper.
7. Needle plate or presser foot with burr.
8. Rough thread tension disc.
Troubleshooting
Possible Causes
High Speed Overlock Machine
Possible Solutions
1. Threading correctly.
2. Install thread support correctly.
3. Adjust lower knife correctly.
4. Adjust or replace knives.
5. Replace the part.
6. Replace the needle.
7. Adjust the height of feed dog.
8. Adjust thread tension.
1. Adjust thread tension.
2. Adjust pressure on presser foot.
3. Adjust the height of feed dog.
4. Adjust or replace knives.
5. Adjust differential feed ratio.
6. Use proper needle to cloth and thread.
1. Adjust presser foot correctly.
2. Adjust looper cam.
3. Adjust looper correctly.
4. Pass thread correctly.
5. Adjust thread tension.
6. Adjust relation of needle with looper.
7. Replace the part.
8. Polish thread tension disc.
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