http://willswing.com/wp-content/uploads/tech_bulletins/TB20161003.pdf

We recently found that the red nico stops that secure the mounting
of the rear triple block on the Sport 2 and U2 sweep wires were not pressed to
the proper dimension on some gliders due to a malfunctioning nico press tool.
Under load, when the VG is engaged, this can cause the nico stops to slip
forward on the cable, changing the VG adjustment and reducing the VG range.