14. TROUBLESHOOTING

 

Problem

Possible cause

Page

6

Uneven seam

• Is the presser foot pressure too weak?

Instruction

 

 

Adjust the presser foot pressure.

manual

 

 

• Is the feed dog too low?

 

 

 

Adjust the feed dog height.

70

 

 

• Is the bobbin scratched?

 

 

 

If the bobbin is damaged, smooth it with an oiled grindstone or

 

 

0625M

replace it.

 

 

 

 

 

 

 

 

7

Horizontal thread tighten-

• Is the upper thread tension or lower thread tension too strong or

 

 

ing not balanced

too weak?

Instruction

 

Upper

Adjust the upper thread tension or lower thread tension.

manual

 

• Does the rotary disc rotate smoothly?

 

 

thread

 

 

Adjust the pre-tension.

84

 

 

 

 

• Is the tension of the thread take-up spring correct?

69

 

Lower

Adjust the tension of the thread take-up spring.

 

• Is the operating range of the thread take-up spring correct?

 

 

thread

 

 

Adjust the position of the thread take-up spring.

69

 

 

 

 

• Is the needle and rotary hook timing incorrect?

73

 

 

Adjust the height of the needle bar.

 

 

Adjust the clearance between the needle and the rotary hook.

76 - 77

 

 

• Is the thread too thick for the needle?

 

 

 

Use the correct needle or the correct thread.

 

 

 

• Is the rotary hook, bobbin case, thread take-up lever or some other

 

 

 

part in the thread path damaged?

 

 

0626M

Repair the damage, or replace the part with a new one.

 

 

 

 

 

 

 

 

8

Large degree of puckering

• Is the upper thread tension too strong?

Instruction

 

(excess tension)

Make the upper thread tension as weak as possible.

manual

 

 

• Is the lower thread tension too strong?

Instruction

 

 

Make the lower thread tension as weak as possible.

manual

 

 

• Is the point of the needle broken?

 

 

 

If the point of the needle is broken, replace the needle.

 

 

 

• Is the needle too thick?

 

 

 

Replace with as thin a needle as possible.

 

 

 

• Are the thread take-up spring tensions too strong?

69

 

 

Make the thread take-up spring tension as weak as possible.

 

 

• Is the thread take-up spring operating range too large?

69

 

 

Lower the position of the thread take-up spring to as low a

 

 

position as possible.

Instruction

 

 

• Is the presser foot pressure too strong?

 

 

Adjust the presser foot pressure.

manual

 

 

• Is the sewing speed too fast?

Instruction

 

 

Use the sewing speed control keys to gradually reduce the

 

 

sewing speed.

manual

 

 

• Is the angle of the feed dog incorrect?

71

 

0627M

Tilt the front of the feed dog down slightly.

 

 

 

 

 

 

 

111

Z-8550A, 8560A