Thanks Russ this is very helpful information. Since my unit is still under warranty I am undecided where to send it to at the moment.
There is also a very good place to have your tag mclaren units repaired here in Germany. It is Hartmut Bayer the former authorized wholesaler for TMA products in Germany (http://www.home-entertainment-perfect.de). Hartmut is an extremly helpful guy holding up strong former TMA tradition. He has also recently joined this forum.