Mr. G, To stake the nut, use a thin screwdriver blade that has been sharpened to a point on the end, somewhat like a rather blunt arrowhead. You want to stake the hollow end of the screw into the slot on the nut. Be careful also, when removing the old screw, as there is a very tiny plunger and spring in the head of the screw that acts as the detent for the windage adjustment - you'll want to reuse that in the new screw.