The tweeter mounting assembly is independent of the upper box. This allows it to move freely (it is attached to the base and ‘suspended’). Correct assembly means the tweeter is located centrally in the aperture and flush with the face. If the tweeter frame and driver have not been installed properly and needs adjustment it may look misaligned, but it does not necessarily mean it is faulty probably more likely that the owner has not set it up precisely. Easier to photograph than describe.
Can you get a good picture to share? I can take some of mine later if it helps.
New foam grilles are available, I think from Tom Tom.
One thing to check is if they have all the original packaging (not just the box but all the spacers and elements inside) as they are a bit complex to move. Installing them is not that difficult but does require care and knowledge. See the thread in the FAQs. Lots of experience on here.
Not a huge amount else to check apart from the obvious condition of cabinets and drivers. Make sure the owner sends the pips that separate the cabinets. Perhaps also check the allen key bolts that fasten the tweeter frame to the base are not gnarled or messed up. Nothing beats talking to the owner see if they understand how they work and go together so they take them apart carefully.
Great speakers, in my view anyway.