sorry the hole in the bolt for the key is rounded the key is fine. I think the PO over torq'd the bolt down
Can you tap a larger Allen bit into the hole and then take it out? If the doesn't work you can cut a slot in it with a Dremel and use a screw driver to remove it. Can you grab the outside with a pair of vise grips? Just a few ideas....
Geez, talk about a lousy way of working up your post count for the classified. This takes the cake!
EDIT: DOH, i see it was fixed