Little something I wrote a while back
Take your phone and go to your camera mode. With your gun on and nothing in the breach look down the feedneck of the gun using your camera. Your eyes should give off a white/purple static light that is visible via your phone screen, only one side will light up depends which side your “clear” or transmitting eye is on. If you see the light this means your eyes are good and should be working, if no light is visible then that most likely means the eyes are bad and needs to be replaced.