[pb68slab]

If you have to drill , remember these screws are Grade 5 or 8 and fairly hard. Use a cobalt drill bit and a slow drill speed. Air-powered drills are way too fast nd will only burn up the drill bit.
I generally go in with a 3/32 pilot drill first. It will walk less and go straighter. Go slow , use oil. Then open it up with a 9/64 or 5/32 , whichever your screw extractor calls for.

 

[pb68slab]

I'm generally opposed to hitting cast aluminum parts with a hammer , but Lisle sells a neat little impact driver just for 1/4in hex bits.