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