Looking for some recommendations regarding cleaning the exterior of the Harman. Whenever I empty the ash pan, I clean the exterior, gets dusty from the dust from the pellet bags. I usually let it cool down, gently brush it off and wipe it with a damp cloth. I notice the finish on the top is looking a bit dull (top). I wondered what others do to clean it to preserve the coating. And is there something I could apply to brighten up or touch up the exterior. Mainly the top portion which takes most of the heat. Thanks in advance.