Being a cabinet maker and wood worker's wife, I would have know immediately that something was wrong with the wood. The signs are pretty obvious. Again, I have been exposed to woodworking and wood all my adult life -- something like that might have been missed. I think, if you look at it from a legal standpoint (and I am NOT advocating litigation or court action at all) if the seller is a business person, he has a responsibility to know! Then again, some people are simply oblivious to what's right in front of them! I think you would be better served by taking a partial refund and being neutral as far as E-Bay is concerned!
Jeanette