As long as it was purchased on
ebay, you can file an item not as described. By your comment you purchased from a dealer on
ebay. If so, it makes no difference. I would email the seller, tell him you want to return due to a musty mildew smell not disclosed and see what he says.
You have 30 days to file with
ebay and get your return shipping paid as well as a full refund. On the roght side of the item purchased, there is a more actions, if you click on it there is a line that says return this item, click on that and follow instructions.
Just for curiosity, who was the dealer?
Personally, I would not keep anything with a mildew, damp, musty smell. It will contaminate everything around it and is also not healty to breathe that smell.