I have tru glo tfo sights on my glock. I was cleaning it one day and the rear sight just decides to fall off. There is an allen screw in the middle of the sight but I can pretty easily push it out of the dovetail. It feels like the sight is plastic. Is it time for new sights? I am happy with the trijicons on my P220. But due to the mostly defensive use of my glock, I am thinking about 24/7 big dots. Any input?