A rule of thumb I was taught when I was about 12 years old, water and electric don't mix. Keep all electrical components dry. Wipe the dash with a damp cloth, after blowing the heavier crud off, and you will have no problems. I remember reading about dashes that failed because Kubota didn't properly seal them against moisture. I think back to my 1963 Corvair Spyder, where the instruments got fogged up on humid days, and they took a very long time to dry out. I also remember some cars that had this problem had a tiny hole drilled in the lens to vent them. I use a very damp cloth to wipe the dash, and when I remember, I spray it first with a foaming cleanser to lift the dirt off the lens. Eventually the lens will get some very fine scratches in it, and they can be polished out if they bother you. Have to keep it in mind that it is a tractor, not a sports car.