5. TROUBLESHOOTING
106
Cause
Check
Remedy
Page
Thread
tension
Zigzag thread upper
thread tension
Adjust the upper thread tension appropriately.
Instruction
manual
Needle bar plate
Vertical and longitudinal
needle bar play
Reduce the needle bar play, or replace the parts.
-
Lower thread retainer
cam
Lower thread retainer cam should be sitting firmly on
lower thread clamp plate roller.
96
Thread scraps and dust
blocking area around
lower thread clamp and
lower thread presser
Clean around the lower thread presser.
-
Lower thread clamp
Lower thread clamping
force
⋅
If the lower thread clamp and lower thread presser
are bent, replace them.
⋅
Check that the screws are tightened.
-
Needle plate
Relation between material
and needle plate
⋅
When using knit material, replace with the –3
needle plate.
⋅
Replace with a needle plate with a smaller needle
hole.
-
Joint sewing
Angle of work clamp
means that material is not
being clamped.
⋅
Replace with short work clamp that matches the
sewing length.
⋅
Use the accessory auxiliary sheet.
⋅
Process the work clamp assembly to match the
joint section. (Attach or remove rubber.)
93
5-3. Uneven seams (1) …… At the sewing start
Cause
Check
Remedy
Page
Installation height
Adjust the upper thread scissors installation height.
93
Upper thread scissors
opening timing
Adjust to an appropriate opening timing.
94, 95
Upper thread
scissors
Upper thread scissors
operation
Apply grease to the inclined face of the opening
cam.
94
Upper thread feeding Thread take-up amount
Loosen the screw to decrease thread take-up
amount so that upper thread does not pull out of
scissors assembly at the sewing start.
101
3999Q
3998Q
Roller
Cam
Screw
Lower thread
clamp
4000Q
Screw
Increase
Decrease