I recall someone saying that some type of spray oil dissolved Loctite. I can't recall if it was WD-40 or what. Barring that, I've used a soldering iron to heat a small screw that was in something that I couldn't put a torch on. As Dennis said, drilling is always an option. I like to drill in a Bridgeport mill so nothing moves and I can use a short carbide dew drill. Just drill the head off....just barely. The drill can be smaller than the head diameter, but it has to be larger than the shank.