Janome AirThread 2000D Professional Service Bulletin page 44

Lower Looper Timing
Locate the 7mm hexagon bolt at the bottom of
the lower looper arm.

To adjust, loosen the 7mm hexagon bolt slightly
at the bottom of the lower looper arm, and

move the lower looper arm into position. Then
tighten the screw. Be sure to check looper to
needle clearance after this adjustment.
44