Did a little bit of work on my 744T myself, cleaning the contacts of the buttons. To no avail, I might add - I need new parts.
It may seem scary at first but it's not such a big deal really - just pay a lot of attention to the screws. The front of the recorder has a small board which also fits the screen. Changing the screen (which I also have to do) is more complicated - but I'm thinking I'll try that too, if I can get the part.
So - I will have to do some repairs to my own unit soon enough - but I'm not getting any help from the local dealer concerning parts. Did you order a new menu button? Where from?
I'd be willing to take some pictures and/or video while repairing my unit, but I need the parts first...
All the best,
Florian