A few days ago, when re-zeroing my 1979-vintage Security Six, I noticed that while it adjusted, my windage screw was without any discernible click detents. While Ruger technically no longer supports the -Six series revolvers, in this case the adjustable rear sight is the common one that they use for most of their adjustable-sight revolvers. Basically, they suspected that wear or accumulated dust/grime/shavings/GSR were inhibiting the adjustment screw's performance, and while likely repairable, it was easier simply to replace the entire rear sight assembly. They were kind enough to immediately send me a complete rear sight assembly, gratis.
Ruger has long been noted for exceptional aftermarket support, and its good to see that exceptional support still exists.
Best, Jon