The hole and threads for the rear guard screw are improperly done in my action. The screw is degrees off perpendicular. How can this best be remedied? Thank you.

There are several ways to go about the repair. You could bore it out and thread it with an oversized screw, you might be able to use something like a heli-coil but I would just TIG weld it shut and drill and tap for the correct size on the proper plane.