It's been a few weeks now since I sent the beat-up, and now naked, M2 off to Werkstatt Wiener in Munich, Germany. It arrived safely.
Last week I got a letter (yes, a letter!) from Herr Wiener telling me what work is needed, and what it would cost me. It seems the film transport and the shutter mechanism needs work. It'll cost me 175 euro, plus 15 euro shipping, and 16% VAT, making the total sum of some 220 euro.
I phoned Herr Wiener today to tell him he could proceed with the repairs (I had asked him to ask for approval if the cost would be over 200 euro). He'll send me a letter with his bank account details, so I can pay him a.s.a.p. Herr Wiener indicated that next week the camera will be ready, so I expect it to be back sometime in the third week of Spetember! I'll order the leather this week.
If all goes well it seems I can bring the M2 to Mongolia in October.
For now Herr Wiener's service seems very swift and responsive. He only speaks German, which makes communicating a little more difficult for me. I don't speak it very often so I really have to force my knowledge of German into my brain and mouth.

Herr Wiener also only corresponds via snail mail or fax, which obviously takes more time. It's moments like this that I realise how influential email has become (I can't remember the last time I actually wrote and sent a letter).