The chartplotter on my boat works fine. But the buttons work via a sealed keypad module. The contacts use (I think) a. Conductive grease. It works fine when the temperatures are 70F (20C) or higher, but not fine when it is colder. I'm fond of that device. I would rather modify it than replace it. I'm looking for a 12v heater pad, no bigger than 1" x 2" x 1/16" that I could add. I think 10 watts would be plenty. I would wire the pad in with a momentary switch, and use it for short period only. Can anyone suggest a good candidate? Motorcycle hand grip heaters seem almost ideal, but at 3x3 inches, they are too big, and I don't think I could trim them to size.