A missing rear sight elevator is a pretty common problem on old .22 rifles, and I'd like to show you how to make a new one using scrap metal and hand tools.
First, make a paper template using another elevator and locate a piece of scrap metal that is about the same thickness as the slot it goes in. Apply some layout dye and scribe the outline of the elevator.

We'll use a fine-tooth hacksaw to cut out the basic part. We can then use a series of files to cut everything away down to the top of the scribe line.

A small triangular file is used to cut in the serrations.

File in each step at a slight upward angle, starting at the bottom. You may have to thin the elevator slightly and it should just fit into the slot—neither snug nor sloppy. Sand it nice and smooth, and splash on a little cold blue to finish it up.

So there you have it, a simple fix to a common problem.
-- Larry Potterfield