RE: threadlock screw
What is the size of the allen driver that the grub needs to nscrew it?
If it is 3mm, you shoule be able to muscle it out without any stripping. The grub will break free with a small "pop" and then simply unsccrew out.
But if it is a smaller allen driver that is needed, say like a 2.5mm or especially if it is smaller, definitely, do the heat trick that Dave mentioned.