For anyone who has experience with dial glass with a printed decal, are there any recommendations on a safe way to clean the class without disturbing the decal? I'm working on a project that has a piece of dirty glass, with a near-perfect decal on one corner, which unfortunately has a lot of dirt around it. I'd like to clean it while avoiding the need to get a new one made, if possible.

Try putting vasoline on the decal, then glass cleaner on the glass.