I had one round out when the wrench slipped. I took a square drive bit from a multipurpose screwdriver and drove it into the bolt head. OS head bolts are sooo soft the bit drives into the bolt head easily and you can then take the bolt out with little trouble. Do youself a favor and get some hardened bolts to replace them with. Heat the bolt will never hurt either. Also another trick for getting steel bolts from aluminum threads is to take a punch the fits on top of the bolt head an smack it very sharply with a hammer. What happens is that the aluminum threads and steel bolts kinda weld themselves together via corrosion. The sharp rap with the hammer breaks this corrosion loose.