Name ring usually isn't a problem. But as suggested, try dribbling denatured alcohol into the threads. Don't use too much, don't get it on the front element as it could run under the edge. If you're planning to clean lens elements (see dust near diaphragm blades) you have to unscrew hood from rear threaded ring, loosen locking screws and unscrew front group which itself may not want to unscrew. This lens also now suffers from oily blades. John