I had a similar issue with our top button flush toilet until a couple days ago. I finally put a few tablespoons of citric acid into the toilet tank and left it to sit overnight in hopes off cleaning all the grime, etc. inside. When I flushed it in the morning and looked into the tank, it and all the moving parts inside were spotless. The leaking/dripping sounds completely disappeared. I mixed a little more citric acid into a spray bottle with water and sprayed it onto everything above the water line in the tank and the whole tank and all the parts look brand new. What a difference it made.