Cats,
I'm sorry, I didn't make myself sufficiently clear in that post - my apologies.
What I was trying (badly) to say was that there are a number of potential data points around airframe repairs. Incident reports would have been one, but you are absolutely correct in that not all airframe damage would have come from an incident - my bad.
On interchangeability of glider parts - I know from bitter experience that even in very expensive military aircraft, it's not uncommon to experience a problem where parts that are designed to be interchangeable aren't - early Hawk canopies were an example. That was just poor manufacturing techniques. For aircraft built in very limited numbers, I wouldn't be surprised if wings weren't interchangeable.
I assumed that Grob wings would be interchangeable because I had been told by an owner that they had gone out of their way to move to a more 'mass production' system for their products, with tighter tolerances and the aircraft designed to make interchangeability easier. As I said earlier, anyone purchasing what was (I think) the world's largest glider fleet of a single type should have mandated interchangeability of major airframe components as a way of ensuring that the fleet would be supportable in service. That was an RAF policy dating from at least the mid 80s.
The biggest problem here is lack of information. I'll hold back on the speculation for now until we get some info out of Coff's sterling efforts. And I apologise for any unwarranted speculation beforehand.
Best Regards as ever to those who know whats going on,
Engines