It'll take me some time to actually get to fixing this, but I'll start this thread so I've got somewhere to make notes as I go. Annoyingly I don't have any of my T&M gear with me where I'm living at the moment.
The seller claimed he'd tested it and it transmits fine. There is no receive audio. That is all I know. The seller did say they hadn't had a go at fixing it. I had a very brief look inside, and at first glance I am the first person in there, so that's something.
I found a service manual without too much drama, but it's 13MB, so can't post it here. Don't have the link on hand right now.
An that absence of better advice I think I'll turn my hand to making or acquiring an extender board to aid with diagnostics. Before I go searching and measuring, does anyone happen to have any docco on the connector specs for boards in this thing?
It's also missing the clips that hold the lid on. Does anyone know what they looked like?