My beloved Nikkor 50mm f/1.8 is giving me some trouble. First noticed when all images shot with aperture significantly smaller than f/1.8 came out almost all white. I then noticed that when I move the little stick the camera uses to set the aperture to "wide open" and release it, it takes a siginificant time for it to move to "almost closed" again just like it would stick a little or the mechanism for moving it back isn't working well anymore. Anyone ever had this problem and can I myself do anything about it or will I have to send it somewhere and what would that approximately cost? There's no more warranty left on the lens. Please help me.