I have a gun with that same lock in it, and here is what I did. I took the springs out of the lock, but left everything else in tact. I put a piece of metal rod between the hook where the spring tip contacts the tumbler, and the bridle, and clamped the whole thing in a vice. Then I got a torch, and a box end wrench that fit over the jaw screw on the cock to use as a lever. I then heated it up just below the jaw, and put a little pressure on the wrench. You can do this with a closed frizzen, and watch where the lower jaw is in relationship to the existing scrape marks on the frizzen.
I must say this helped, but I still had inconsistent ignition, until I adapted the frizzen off of an old Dixie F1 flintlock to this lock. Halfsoling the frizzen would probably work as well. My gun is now more reliable than my percussion guns.
Hungry Horse