GamuT D-200 Problem

I have a 15 year old GamuT D-200 that recently lost about 90% of the power from the right channel.  A local high-end repair shop told me they do not work on GamuT because the circuitry is so unique (he had tried to repair one before and failed).  The repair shop asked me to contact GamuT to see if they could guide us to the problem and repair.  I contact GamuT but got no response.

A.  Has anyone had/seen such an issue?
B.  Does anyone know of a shop able and willing to repair?
I live in Sarasota FL so drop off would be best as it weighs a TON.