I've posted before that I have to replace the fly in my Cherry Corners lock. The hammer screw won't budge. I have to get it off to get to the fly.






I've been soaking it in PB Blaster for a week, still won't move.
I've use a hammer to tap it, still nothing.
Someone suggested an impact driver, but I'm afraid it'll rip out the slot in the screw.

My next step is applying a pencil butane torch to the screw, but I'm worried about the temper.

Any thoughts.