I picked up a secondhand natural AB1 a while back. All in all it is in pretty good shape, but it has some very noticeable dings in the back. the only appear to be in the finish and don't actually dent the wood. is this somethig that can be easily repaired or would it require a complete refinish? since they're on the back, if there's any major work involved I'd just leave it as is, but it'd be nice if it looked as good as it sounded.