Apply penetrating oil and let it soak
Center-punch the broken screw
Drill a small pilot hole into the screw
Use a left-hand drill bit if available
Insert a screw extractor and turn counterclockwise
Grip any exposed shank with locking pliers
Cut a slot in the screw and use a flathead screwdriver
Heat the surrounding metal to help loosen the threads
Tap the screw lightly to break corrosion
Weld a nut onto the broken screw and remove it
Drill out the screw completely
Re-tap the hole or use a thread insert if needed