White 447 - Troubleshooting Guide

12.TROUBLE
CHART
PROBLEM
PROBABLE
CAUSE
CORRECTION
Breaking
lower
Thread
not
wound
evenly
on
the
bobbin P.
9,
p
13
thread
or
not
drawn
up
correctly
Lower
thread
tension
too
tight
P.
1
1
Lint
stuck
in
the
bobbin
case
and
inside Remove
lint
the
tension
spring
and
fluff
with
a
cleaning
brush
Skipping stitches
Needle not
fully
inserted
P.
6
Needle bent
P.
6
.
Size
or
type
of
needle and
thread
not
P
14
suitable for
the
material
Incorrect
upper
threading
P.
12
Too
much
oil
on
the
hook
P.
26
Irregular
stitches
Incorrect
size
of
needle
for
the
material
P.
14
Upper thread
tension too
loose
P.
1
7
Incorrect lower
tension
P.
1 1
The
material
not
Incorrect
feed dog
height
p.
1
1
fed
correctly
Lint
stuck on
the
feed
dog
P.
25