The ASW-20 list has many threads about
communication difficulties with Centrair.
That said French owners seem able to get
service - speaking the same language in
the same time zone can help.

We put a CG hook on our newly acquired
G-103A and discovered on the next annual
that an AD requires new mounting plates.

LTB Lindner supports Grob gliders and
supplied the needed parts with no more
than the usual delay at a reasonable for
aircraft price. They communicate well in
English.

We are happy with the robustness, it's
overbuilt, and flying qualities.