Rigging Question

My glider requires a small amount of top rudder to keep coordinated in
a left turn. A right turn seems to require the appropriate amount of
right rudder. The glider flies straight and level ok with maybe a
minor amount of right aileron and left rudder. Wing incidence is close
(.1 of a degree) between the right and left with the method I used to
check.

Any wisdom out there which may heve suggestions about what to do next.
18M glider with half span flaps and full ailerons to 6 inchs from tip.