Pfaff select 1520, Service Manual

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11. Zero point adjustment of stitch length regulator
Requirement:
When the stitch length graduated dial is set to "0", the feed dog should only move up and down.
Check:
z
Set the stitch length graduated dial to "0".
z
Place a piece of fabric under the presser foot.
z
Lower the presser foot.
z
Operate the machine.
The fabric must not be fed neither forwards nor backwards.
Precondition 1:
The dot markings on the toothed segments must be diametrically opposite each other (fig. 17).
Precondition 2:
Eccentric 40 must be in its basic position facing upwards (fig. 18).
Adjustment:
z
Loosen screw 41 with a 5.5 mm spanner.
z
Re-position screw 41 until the center lines of the bolts in actuating crank 39 and linkage 42 and rod 43
are level (see dot-dash line).
z
Tighten screw 41.
Cross-check:
z
As described under "Check".