If the damage is noticeable and is not obvious in the listing picture or not mentioned in the listing,I suspect Ebay should refund you. It could be that the item was also damaged during postage - a box is not simply enough if not enough soft packing material also used. In that case,it is the seller's responsibility
IIRC.
Regarding the musical item - I would contact the seller and see what they say first. Having looked at what happened to that Violin sale on Ebay,which was very sad,you might be OK there too.