Yes this particular type of dial can be cleaned depending the areas affected. It requires care and the use of stereo magnification, Such as a microscope or at least an optivisor. This dial would be spot cleaned using a mild window cleaner on a extra small makeup applicator. Great care must be taken to avoid touching any of the printed areas or applying too wet. These are the only areas I would do. As soon as these areas are cleaned work should stop, you don't want to over clean.
Please understand, I consider this dial to be pretty good to begin with and would want to have it in hand before deciding to clean.
Here is a Dial that necessitated cleaning and the pros outweighed the cons.