Brother KE-484C Instruction Manual page 65

16. TROUBLESHOOTING
Problem
Upper thread breaks.
Lower thread breaks.
Skipped stitches occur.
Needle breaks.
59
Cause
Upper thread tension is
too strong.
Needle is installed incor-
rectly.
Thread is too thick for the
needle.
Thread take-up spring
tension and height are
incorrect.
Damaged or burred
rotary hook, needle hole
plate or needle.
Thread melting (synthetic
thread)
Lower thread tension is
too strong.
Corners of needle hole
plate is damaged.
Clearance between nee-
dle and rotary hook tip is
too great.
Incorrect needle and
rotary hook timing.
Upper thread is too short.
Needle is bent.
Needle is installed incor-
rectly.
Needle is touching the
rotary hook.
Needle is bent.
Needle is too thin.
Check
Upper thread tension
Needle direction
Thread and needle
Thread take-up spring
tension and height
Damage or burring
Thread edge
Lower thread tension
Damage
Needle clearance
Needle bar lift amount
Thread take-up lever
stroke
Bent needle
Needle direction
Needle clearance
Needle bar lift amount.
Bent needle
Needle and thread
KE-484C
Remedy
Adjust the upper thread
tension.
Install the needle cor-
rectly.
Use the correct thread for
the needle.
Adjust the tension and
height of the thread take-
up spring.
File smooth or replace
the affected part.
Use a thread cooling
device.
Adjust the lower thread
tension.
File smooth or replace
the needle hole plate.
Adjust the needle clear-
ance.
Adjust the needle bar lift
amount.
Adjust the thread take-up
lever stroke.
Replace the needle.
Install the needle cor-
rectly.
Adjust the needle clear-
ance.
Adjust the needle bar lift
amount.
Replace the needle.
Use the correct needle
for the material.
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