Put some Brake or Carb cleaner on a rag and clean the interior of the distributor body. Use compressed air then to blow out the remainder and dust. It would be better, although more involved to remove it from the engine. Also, put a drop of
oil on the flyweight pivot points. The Carb or Brake cleaner will not harm the nylon or plastic pads and various other small pieces within the distributor, nor the cap or rotor.