Can you be more specific about what make you think it might have been cleaned? Somrthing is going on there. I first thought it might be on the slab, but there seems to be a mark at the corresponding place on the reverse. Also appears to be a small die crack at 2-3 on the obverse. Nothing wrong with that. Just noted.
We are a bit ff-topic: I think that you should determine your collection. If you like it, then you should get it. As I said earlier, hitting the slab that hard is a bad idea, and maybe lightening the hits could help keep the slab intact