Out of curiousity, have you taken the lock out and played with it and if so, does it work well outside of the gun? If so, then what happened was after the gun left the factory, the wood was subjected to climate change caused by your area and some of the wood may have "swollen" (or it continues in its "drying" or "warping" process). In that case, the lock is fine and more wood needs to be removed.
You can blacked the suspected moving parts and refit the lock. Cock and and snap it (use a piece of wood as a substitute for a flint) several times and then remove the lock. Where you see "black", you can remove with a carving knife (or shhh.... very light application with a dremel). You then reblacked the parts and restore it to the gun and test again. Repeat as often as necessary.