PS: I think one of the main reasons we see screw heads messed up is the slots were not carefully and completely cleaned out before trying to turn them. And a lot of the hundred year old gook in a slot is rock hard. An Exacto blade will clean them up nicely. I usually use a thin piece of brass sheet I’ve cut into a V point to dig it out.
Totally agree with this statement. Some of the screw slot depths are not very deep to start with so if they are half filled with hard crud, it sure doesn't leave much for applying pressure with a turnscrew.
