Been there, done that.
My sight was such a piece of crap I just went ahead and replaced it with a Volquartsen Bomar type adjustable. Even finding one on sale, they are expensive. I think I paid like 62 bucks for mine from Rimfiresports.
What you can do is....
Loctite it in place with blue or green loctite. You might as well do the front sight as well, as they come loose too.
You can replace it.
You can use a center punch on the bottom of the sight to raise up some teeth on the sight and then loctite it in place.
You can get a rail and reddot set up.
You can get angry and smash things.
An enlightened zeal for the energy and efficiency of government will be stigmatized as the offspring of a temper fond of despotic power and hostile to the principles of liberty.
Alexander Hamilton, author of Federalist No. 1. 10/27/1787