A few years ago I noticed dots that I didn't remember being there. The scope was on a rifle I don't shoot as much. I knew that these two extra dots weren't on my other scope.
Well, lo and behold when I took my rifle out in the cold the other day, I noticed a bunch of extra dots appearing along the reticle wires. Now I knew that these ones hadn't been there before as I use this scope a lot
Today I took out the reticle cell and opened it up. I hadn't really looked at them closely before, but they are just threaded together with an o-ring in the middle. Sure enough a tiny amount of oil had found its way into the reticle cell! I'm not sure how it got there as I don't put oil the scope but maybe some wiping fluid ended up on the scope body somehow.
Fortunately a couple of minutes with an eye glasses cleaning kit and the reticle is as good as new. I'm quite glad because those extra dots were distracting.
I thought I'd post this as it might come in useful to someone someday.
Chris.