If the hole is out of round, or if your new hole is going to take close to half of your original hole, just drill it out to the next common thread size, if it's drilled ok, but just in the wrong place, tap it and locktite in a piece of threaded stock. file it flat, center punch and drill your hole in the right place. A specialty fastener store can get you aluminum bolts to use for filling this hole, (some states use on their road signs) that would make it easier to drill with out the bit wanting to "walk" to the softer metal..