I see no reason to send the lens back and I doubt anything is massively wrong with it. You've got what, 4 major lens groups to worry about with only 2-3 real ways to screw it up? Seems like you could just exchange elements around until you have "sharp enough" images. Although not razor, the lily looked fine.
Great question - I did not realise they were different. The inner lens do not have any pencil marks, so I will label them myself and take 2 photos to compare. Should these be at infinity or is closer up ok? Infinity photos are problematic at the moment, so I would prefer a stobe illuminated target.
Contrary to popular belief the lens is not imbued with magical powers and assembled by elves in the forest. I'm sure he can get it back together and up to snuff again. Take control.