Barrels hook will not release from cocking lever?

[Brush Buster]

Good Morning Kenny , I have no idea why this is but over the years I have owned more than a few Parker Guns that the barrels wouldn't lift off ,but If I dried Fired the gun and dropped the hammers ,they would come off as smooth as silk ! Did you happen to try this before removing the screw ? Maybe Brian or someone that actually Gun Smiths on here would have the reason why , I don't but I know that always worked for me on the guns that just wouldn't lift the barrels !