Brother TZ1 B651 Basic Repairs & Adjustments page 25

TROUBLE SHOOTING FOR LOCKSTITCH
THREAD TAKE UP FAULTS
Take up lever loose
Take up lever breaks
TENSION FAULTS
Bobbin thread pulls up to the top
Needle thread draws under materials
Thread bunches up or cobbles under materials
THREAD FAULTS
Thread breaks
Thread frays or shreds
SEWING MACHINES
Possible Fault
Internal cam lift screws loose
Lever hitting take up lever guard
Possible Fault
Bobbin incorrectly inserted in bobbin case
tension spring
Bobbin tension too loose
Bobbin case tension spring too weak
Needle thread tension too strong
Upper threading is incorrect
Thread catching on thread stand or unit
Needle too large
Incorrectly threaded
Tension release operating too early
Not holding thread ends at start of the sewing
operation
Damaged hook or thread catcher
Dry hook and bobbin base
Damaged bobbin case retainer
Operating knee lift when sewing opening
tension release
Incorrectly threaded
Tension release operating too early
Not holding thread ends at start of the sewing
operation
Damaged hook or thread catcher
Dry hook and bobbin base
Damaged bobbin case retainer
Operating knee lift when sewing opening
tension release
Possible Fault
Upper threading incorrect
Needle incorrectly inserted
Damaged needle
Needle thread tension too tight
Hook timing incorrect
Damage on hook
Damage on needle plate
Damage on bobbin case
Thread guides damaged
Thread quality poor
Check spring timing incorrect
Needle bar height incorrect
Bobbin tension very tight
Bobbin bent or damaged
Upper threading incorrect
Needle incorrectly inserted
Damaged needle
Needle thread tension too tight
Hook timing incorrect
Damage on hook
Damage on needle plate
Damage on bobbin case
Thread guides damaged
Thread quality poor
Check spring timing incorrect
Needle bar height incorrect
Bobbin tension very tight
Bobbin bent or damaged
Possible Remedy
Tighten cam lift screws
Reset or replace the guard
Possible Remedy
Remove thread and re insert into bobbin case
spring correctly
Adjust tension
Replace spring or bobbin case
Reduce needle thread tension
Re thread machine correctly
Remove cop or cone of thread and sett thread
stand up correctly
Replace with correct size needle
Thread correctly
Adjust tension release
Hold BOTH thread end when commencing a
sewing operation
Remove the damage to hook or thread catcher or
replace the hook assembly
Oil the hook bobbin base and raceway saddle
Remove damage to retainer or replace retainer
DO NOT MOVE KNEE LIFT WHEN SEWING
Thread correctly
Adjust tension release
Hold BOTH thread end when commencing a
sewing operation
Remove the damage to hook or thread catcher or
replace the hook assembly
Oil the hook bobbin base and raceway saddle
Remove damage to retainer or replace retainer
DO NOT MOVE KNEE LIFT WHEN SEWING
Possible Remedy
Rethread correctly
Replace needle and fit correctly
Replace needle
Adjust needle tension
Adjust hook timing
Remove damage to hook or replace hook
assembly
Remove damage or replace needle plate
Replace bobbin case
Remove damage or replace thread guides
Change to a better quality thread
Adjust check spring timing
Adjust needle bar height
Remove bobbin case and rethread correctly adjust
bobbin case tension
Fit new bobbin
Rethread correctly
Replace needle and fit correctly
Replace needle
Adjust needle tension
Adjust hook timing
Remove damage to hook or replace hook
assembly
Remove damage or replace needle plate
Replace bobbin case
Remove damage or replace thread guides
Change to a better quality thread
Adjust check spring timing
Adjust needle bar height
Remove bobbin case and rethread correctly adjust
bobbin case tension
Fit new bobbin
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