Janome AirThread 2000D Professional Service Bulletin page 55

Upper Looper Timing
If an adjustment is needed, loosen the 2.0mm hexagon screw, slide
Upper Looper Clearance
the upper looper left or right to obtain the 8.0mm clearance. Hold

the looper and tighten the 2.0mm screw.
When the upper looper is moving upward, the clearance between the
tip of the upper looper and the back of the lower looper should be

between 0 - 0. 01mm. To make an adjustment, loosen the 2.0mm
screw on the upper shaft, obtain the correct clearance then tighten
the screw.
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