Pfaff 1540 User Manual
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38. Adjustment of thread check spring stroke
The thread check spring prevents the descending needle from piercing the slack needle thread. The
needle thread is slackened by the descending take-up lever.
Requirement:
Thread check spring 126 must keep the needle thread taut at least until the needle point enters the fabric
(fig. 77).
The thread check spring must release the needle thread as soon as the lower edge of the needle eye ent-
ers the fabric.
Check:
z
Press the straight stitch button.
z
Set stitch length to "6.0".
z
Place two layers of fabric under the presser foot.
z
Sew a few stitches.
z
Turn the handwheel and determine the end of the thread check spring stroke.
Correct slackening of the needle thread takes place when it enters the needle eye not tautly but in a
loose curve.
Adjustment:
z
Loosen screw 128.
z
Turn thread check spring stop sleeve 127 until thread check spring 126 is in the correct position.
z
Tighten screw 128.
Cross-check:
z
Sew a few stitches and proceed as described under "Check".