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TROUBLE SHOOTING FORLOCKSTITCH
FEED DOG FAULTS
Feed dog touches the needle plate
Feed alignment incorrect
Feed dog breaks
HOOK FAULTS
Hook jams
Hook and bobbin base` area noisy
Hook timing keeps going out
Machine jams easily
NEEDLE FAULTS
Needle plate centre bends
Needles bend
Needles break
Needles fall out of needle bar
SEWING MACHINES
Possible Fault
Misaligned feed timing and position
Loose feed dog screws
Loose feed dog link mechanism
Feed dog hitting needle plate
Possible Fault
Thread caught in the hook raceway saddle
Needle piece or part of a pin caught in hook
raceway
Bobbin base or hook saddle raceway badly
work
Loose or damaged hook screws
Thread gets jammed in bobbin base raceway
Hook raceway badly worn
Lack of oil in hook raceway
Thread tension release setting incorrect
Machine incorrectly threaded
Possible Fault
Needles too big for needle plate hole
Bent needle
Feed dog too high
Work too thick for needle
Needle too thin for work
Needle plate hole too small for needle size
Needle too thin for work
Needle plate hole too small for needle size
Hook timing incorrect
Feed timing incorrect
Bobbin case incorrectly located
Bobbin base comes out of bobbin base finger
Groove in the end of the needle clamp screw
Possible Remedy
Realign and retime feed mechanism
Tighten feed dog screws
Tighten feed dog link mechanism
Reset fed dog alignment height or timing
Possible Remedy
Remove bobbin base and thread
Remove bobbin base and damage to hook, and
adjust hook timing if necessary
Replace hook
Replace screws
Replace hook
Replace hook
Put a spot of mineral oil in the hook raceway
Reset tension release mechanism
Rethread correctly
Possible Remedy
Enlarge needle hole
Replace needle with correct size
Replace needle
Adjust feed dog setting
Replace with a adequate size and type of needle
Replace with correct size and type of needle
Replace with correct size and type of needle
Replace with correct size and type of needle
Replace with correct size and type of needle
Retime hook
Reset feed timing
Relocate bobbin case
Reset hook to bobbin base setting
Replace needle clamp screw
17:7
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