Just to provide an update on my experience finding a repair for my Hexar RF - and some good news for continued availability of RF repairs.
I eventually sent it to Bellamy Hunt at Japan Camera Hunter:
Bellamy forwarded it to Sony (Konica Minolta) for the repair. The original estmate to repair the 'Error Code 10' problem was ¥15,000 - plus Bellamy's ¥5,000 handling fee.
However - after examining the camera Sony said it needed full replacement of the shutter system, rather then replacement of the one part normally associated with the Error Code 10 fault. The price for this was almost double the original estimate, at ¥29,125 (plus than handling fee).
So eventually it was more expensive than expected - but still not excessively expensive. And hopefully the new shutter mechanism will have some good life in it.
Bellamy Hunt's service was excellent - and speedy too. The whole process from shipping from the UK to Japan, to receiving the repaired camera back took exactly one month.