4
Causes of Trouble and Troubleshooting
21
1) Sewing machine troubleshooting
No Symptom Checkpoints Root cause Corrective action
Direction and
height of needle
Needle
Needle bar
ascending level
Needle bar height
Gap between
needle and hook
Threading
method
Needle
Direction and
height of needle
Upper thread
tension
Lower thread
tension
Working capacity
of take-up lever
spring
Direction and
height of needle
Needle
Threading
method
Needle bar
ascending level
Needle bar height
Gap between
needle and hook
Thread take up
spring
Needle
breaks
Thread
breaks
Sewing is
skipped
The upper
thread does
not rotate
The lower
thread does
not rotate
Upper thread
falls out when
starting to sew
1
2
3
4
5
6
Needle is inserted into wrong position
Needle is bent
Bad timing of feed dog
Bad timing of needle and hook
Bad timing of needle and hook
The gap between needle and hook is
inadequate
Wrong threading
Bent needle or broken needle tip
The direction and height of the needle
inserted is wrong
Too tight upper thread tension
Too tight lower thread tension
Too much working capacity
The position of the needle inserted is
wrong
Bent needle or broken needle tip
Wrong threading
Bad timing of needle and hook
Bad timing of needle and hook
The gap between needle and hook is
inadequate
The length of the remaining upper thread
is too short
The spring is not strong enough to pull
out the lower thread
Too tight upper thread tension
Too weak upper thread tension
Tension of upper thread is too weak
Tension of lower thread is too strong
Strong upper thread tension
Needle is too thick for thread
Reinsert the needle correctly
Change the needle
Adjust the timing of feed dog
Adjust the timing of needle and hook
Adjust the timing of needle and hook
Adjust the gap between needle and hook
Thread the needle correctly
Change the needle
Insert the needle correctly
Adjust the tension of upper thread
Adjust the tension of lower thread
Adjust the stroke level
Insert the needle correctly
Change the needle
Thread the needle correctly
Adjust the timing of needle and hook
Adjust the timing of needle and hook
Adjust the gap between needle and hook
Adjust the adjustment volume of the
upper thread
Adjust the stroke level
Decrease the upper thread tension
Increase the upper thread tension
Increase upper thread tension
Decrease lower thread tension
Adjust upper thread tension
Check the needle