Is their locktight on a FWB 65 sight spring screw?

[45flint]

Replacing a sight spring on the rear sight and the retaining screw doesn't want to let loose from the body. Is their a chemical locktight I need to heat?

[45flint]

Well, I could not get the hex screw that held the broken back sight leaf spring to let loose, came close to stripping the head. Could not effectively heat it with a soldering iron so I bought a micro butane pencil torch. Did the job perfectly, there was a white locktight of some kind locking it in place. New spring is in place and it works perfectly. That little ball bearing in the sight is a hard one to contain!!

I wonder if the locktight is a sign that the gun was stripped down to change the inner seal. I assume if FWB used locktight someone here would have known?