Apart from the usual drill / ezy out (there's a laugh) / tap / heat methods, is there some nifty way of getting a hex / allen screw out when the hex hole has been rounded out and won't take the key? <br /><br />It's a recessed head, the top of which is flush with the part it's holding, so I can't get at it from anywhere except above.<br /><br />We're talking pretty tough steel on a mulcher blade.