Definitely sounds like the buyer is angling for a discount or a freebie - judging from their lame excuses.  And am sure they have done this loads of time and have perfected the best of wording of their complaints.

Selling overseas is much more difficult, especially as the buyers over the pond know the eBay complaint system like professionals.  And am sure a lot of buyers know a lot of sellers cave in to pressure about their item.

As the others have advised you need to be extra sure you follow the correct procedures so you either get your item back or buyer doesn't want any more cases on their a/c.

You will need to be as 'pernickity' as your US buyer.  And really re-consider selling outside the UK unless you are prepared to give your stuff away to those who are serial scambugs who play the system.

When I've had to deal with these types I've contacted other sellers to ask if they had any 'problems' with the buyer.  Some replied, some didn't.  But discovered those that had replied had problems and I used that info when reporting the buyer for abusing the mbg.  I reckon your buyer was hoping to get an antique they could re-sell for mega bucks in the US rather than an Edwardian item.

Hope it works out for you!