22.
Trouble
Shooting
Skipping
of
Stitches
Cause
Wrong
needle
system.
Needle
bent.
Needle Inserted incorrectly.
Incorrect
threading.
Thread
Breaks
Cause
For
any
of
the
reasons
indicated
above.
Thread
tensions
too tight.
Knotty
thread.
Needle
poiT^blunt
or
damaged.
Thread
snarled
up.
Faulty
Stitch
Formation
Cause
Improper
tension.
Wrong
needle
size
and/or
thread
used
Pieces
of
thread
between
tension
discs
or
under
bobbin
case
tension
spring.
Needle
Breaks
Cause
Wrong
needle
system.
Needle
bent.
Needle
too
thin.
Machine Works Heavily
Cause
Lack
of
oil.
Wrong
lubricant.
Hook
race
obstructed
by
pieces
of
thread.
24
Remedy
For
correct
needle
system
see
Chapter
8.
Insert new
needle
as
instructed in
Chapter
9.
Orient
needle
so that its
short
groove
faces
toward
the
sewing
hook.
Thread
needle(s)
as
instructed
in
Chapters
7,
10.
19
and
21.
Remedy
See
remedies
listed
above.
Regulate
tensions
as
instructed
in
Chapter
12.
Use high-quality
thread
only.
Replace
needle.
Check
upper
threading
from
spool
of
thread
to
needle.
Remedy
Regulate
tension
as
instructed
in
Chapter
12.
Correlate
needle,
thread
and
fabric
as
shown
in
table
in
Chapter
8.
Remove
thread
and
re-adjust
tension
as
in
structed
in
Chapter
12.
Remedy
Insert
needle
of
correct
system
as
instructed
in
Chapter
8. . .
Insert
new
needle.
Insert
thicker
needle.
Remedy
Oil machine
as
instructed in
Chapters
3. 16
and
18.
Use only non-resinous and acid-free sewing
machine
oil.
Try to free the jammed thread
as
you rock
the
balance
wheel
back
and
forth.
If
this
action fails,
dismantle
the
sewing
hook
as
instructed
in
Chapter
16.
Contents
1.
General
2. Setting Up the Machine
3. Cleaning and Oiling
4. Test-Running
5.
Removing
the
Bobbin
Case
.
6. Winding
the
Bobbin
7. Threading and Replacing the Bobbin Case
^
Selecting
the
Correct
Needle
.
9.
Changing
the
Needle
. .
10. Threading the Needle
....
11. Drawing Up
the
Bobbin
Thread
12. Regulating the Thread
Tensions
.
13. Regulating the Stitch Length .
14. Regulating the Pressure on the Material
15. Changing the Feed Dog
....
16. Cleaning the Sewing Hook
17. Changing the Vibrating Presser
18. Adjusting the Foot Lift
....
Additional
Instructions
for
Pfaff
342,
344
and
346
two-needle,
cylinder-bed
sewing
machines
with
right-hand
balance
wheel
and the
Pfaff
354
two-needle
machine
with
left-hand
balance
wheel
19.
Upper
Threading
of
Two-Needle
Machines
"^Cleaning
the
Sewing
Hooks
of
Two-Needle
Machines
Additional
instructions
for Pfaff machines 343
U-12/02
and 343
U-12/03
21.
Threading
the
Needle
of the
Pfaff
343
U-12
22. Trouble Shooting
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