AFAIK what is wrong (at least with the pure gliders - the Vikings) is the paperwork, and how it is wrong differs from glider to glider. Therefore the only way to get it right is to go through each glider with a magnifying glass to make sure it has all the mods it should have, and that any repairs (documented and undocumented) are done correctly. I can imagine the only way of ensuring the later is to redo them...