[universalgrl]

As I was a master aircraft technician I learned the correct way to extract frozen screws.
I saved ALL the screws on my carriers front plate including the 4 1/4 inch screws for the log book holder.
Use a penetrant of your choice (over several days) I use wd-40. Use a dremel with a fibre wheel to clean out the screw slot and remove burrs, make sure the sides of the slot are parallel to each other.
Make sure your tool bits are sharp and don't show any signs of twisting, the bits can cam out otherwise wrecking the screw slot.
Impact hammer with the extractor and appropriate bit or hand held impact and a zero bounce hammer.
If all else fails MIG a tack weld on the screw and attack the fastener on the other side, nuts are cheap.