u/BlueEyesssss

I only got this like two years ago and noticed that it looked as if the gasket plug was moving out of place on one side but upon opening it up the gasket hasn't moved at all, what I did find however is on the side it looks like it's rising up on the gasket is yellowing and hard. I'm not understanding how this happened within a few years and I'm even more concerned because I'm not sure how I'm supposed to replace this when inevitably fully degrades (I assume it's some kind of dry rot not sure how or why it happened but it makes sense)

As this is a rotating globe if it's going to be replaced it has to be the type of gasket that rotates but I can't find those anywhere