I want to replace the rear sight (K frame) elevation nut (screw head) and any other part that needs it. I have parts, but see there is retaining ring and small loading spring. How is disassembly and reassembly done? Thanks.

If you don't have spares for all of the parts, don't lose any
It's not a bad idea to do it in a large paper grocery bag.

The square threaded part on the bottom can screw right off.
Pry the spring clip off of the elevation nut.
Slowly remove the elevation nut through the top (the plunger and spring will soon be released)

Replace the elevation nut (the spring and plunger will have to be pushed in to clear and be held by the rear sight leaf)
Flip it over and replace the spring clip onto the part of the elevation nut that sticks through.
Thread the square threaded piece back in
Replace it on the revolver and adjust.

You know, it's a lot easier to do than describe

Thanks. I just returned to the computer after doing it.

Just like you said, did it in a box after I lost one plunger. Now going to find it, using 500 lumen light and prayers.

It is easy to do! Why do they make the screws so easy to bugger up? I now only use the SW coin screwdriver to adjust sights.

Found that little plunger! Thanks again, and
Semper Fi!