I have come into a lot of Lego controllers and other devices that have had batteries left in them for years. What is the best substance for removing corrosion? Most of the device contacts are not destroyed and would work if the corrosion was removed and the contacts properly cleaned. I have fixed this kind of thing in the past by patiently scraping with a small screwdriver but because of the quantity and difficulty of reaching the contacts, I am hoping for a magic spray-on solution, similar to rust remover. Does anyone have suggestions for this?