Praise be to the power of the Internet, and the Hive Mind that inhabits Ars Technica. I posted there, enquiring about the lens options for the D80, as I’d like to avoid spending too much on the replacement for the 5D. A reply by kefkafloyd supplied me with information I’d been unable to find anywhere else, and apparently it was unknown to the authorised Konica-Minolta repair center in the UK – namely that the issue I’ve been having is a known (internal repair documents) design flaw in the KM 5D and 7D cameras.
I’ll be having another chat with the manager of Jessops when I’m back in the store playing with the Pentax and Nikon – according to those same internal documents, something like 25% of the 5D population is affected by this flaw.