Do someone sugested to apply cold? I think epoxy ar very stable at low temperatures, so I think is not a viable option.
The epoxy is stable but can get brittle at very low temps, so may crack and free up the threads when you apply torque to the screw. The primary reason I suggested freezing the screw was to quickly shrink it by contracting the metal. That bit of shrinkage in the major and minor diameters of the threads may allow you to turn the screw out. You would need to freeze just the screw very quickly and get the temp very low for this to work. I was thinking about the liquid nitrogen guns with pinpoint control, such as dermatologists use to burn nasty things off your skin. Not worth buying the equipment, but if you have a physician friend, see if he will zap it for you.
