Thanks Dale! Since I initially posted this I've managed to get the screw in the focus ring out ( even though the slot resembles a drainage ditch) and found out there has been severe interference of the stud portion of that screw and the rear slot face in the scope body - think of something resembling broken off rake teeth! Since the optics are still very nice I'll see if I can find a replacement screw at my LGS and file the rear slot face true before giving up on the DIY . Thanks again, Chuck.