Rear sight help!

[SecretNY]

Hi guys, I run a 10-8 Performance front and rear in the .125 width on my G17. I'm interested in swapping to the .140 width, but encountered a problem with my rear sight. The gunsmith at the time looks like they used red loctite on the sight. I cannot get the screw out using my 1/16 allen key. Anyone have any ideas (the gunsmith has since moved...)?

Thanks!
SecretNY

[jmart]

Apply heat. Hit it with a torch.

[SecretNY]

Thanks!