The mainspring screw seems really stuck on a recent pickup that I'd like to tear down and give a good cleaning, an 1849 Pocket Revolver. I do have good hollow-ground bits that fit, but feels like it is taking much more effort than necessary to break it free and don't want to snap the head off. Maybe a good soaking in 50/50 ATF/Acetone will do it? Any other words of wisdom?