8. TROUBLESHOOTING

 

Problem

Possible cause

Page

5

Skipped stitches at sewing

・ Is the thread take-up spring tension too strong?

*

 

start

Reduce the tension of the thread take-up spring.

 

Thread unravelling at

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

 

 

sewing start

Lower the position of the thread take-up spring.

*

 

 

・ Are the trailing lengths of the upper threads too short after thread

 

 

 

trimming?

 

 

 

Adjust the pretension.

 

 

 

・ Are the threads not being trimmed cleanly?

27*

 

 

Sharpen the fixed knives, or replace the fixed and movable

 

 

 

 

 

knives if necessary.

 

 

 

・ Is the needle too thick?

 

 

 

Try using a needle with a count that is one lower than the

 

 

 

current needle.

 

 

 

・ Is the length of thread trailing out from the bobbin case after thread

 

 

 

trimming too short?

 

 

 

If the bobbin is spinning loosely, replace the anti-spin spring in

 

 

 

the bobbin case.

 

 

 

・ Is the sewing speed too fast at the sewing start?

 

 

 

Set the operation panel so that slow start is enabled.

21*

 

 

・ Is the needle up stop position too high?

24*

 

0749M

Adjust the needle up stop position.

 

 

 

 

 

 

 

6

Uneven seam

・ Is the presser foot pressure too weak?

 

 

 

Adjust the presser foot pressure.

 

 

 

・ Is the feed dog too low?

 

 

 

Adjust the feed dog height.

30*

 

 

・ Is the bobbin scratched?

*

 

 

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

 

 

replace it.

 

 

0473M

 

 

 

 

 

 

7

Large degree of puckering

・ Is the upper thread tension too strong?

 

 

(excess tension)

Make the upper thread tension as weak as possible.

 

 

 

・ Is the lower thread tension too strong?

 

 

 

Make the lower thread tension as weak as possible.

 

 

 

・ Is the needle tip blunt?

 

 

 

Replace the needle if it is blunt.

 

 

 

・ Is the needle too thick?

 

 

 

Replace with as thin a needle as possible.

 

 

 

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

 

 

 

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

*

 

 

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

 

 

 

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

 

 

 

position as possible.

*

 

 

・ Is the presser foot pressure too strong?

 

 

 

Adjust the presser foot pressure.

 

 

 

・ Is the sewing speed too fast?

16*

 

 

Gradually reduce the maximum sewing speed using the

 

 

operation panel.

 

 

 

・ Is the angle of the feed dog correct?

30*

 

0978M

Tilt the front of the feed dog down slightly.

 

 

 

 

 

 

 

35

S-7000DD