I have removed stubborn stripped screws with a pair of plain vise grips with good jaws. Of course, the screw has to have a shoulder like a machine screw, and not a countersunk like drywall screws. Just get the jaws good and tight and all the way down to the aluminum and twist backwards slowly. Of course, it doesn't always work, sometimes breaks the head off, sometimes strips off itself, and other methods of failure, but with a little luck, and maybe a little PB Blaster to soften it up, but be careful, as the PB may damage surrounding finish.
Good luck. You will need some.
Steve