I have repaired these switches before after falling victim to a leaky sunroof. Disassembly is fairly easy. You can find instructions on YouTube. Once you have the part in your hand, you can test the switches with a DMM. Each switch has two contact points. In my case, water had infiltrated the board and a plated thru hole connection was open. I shoved a piece of bus wire thru the hole, soldered it on each side and bingo the switch started working. I'm located outside of Detroit. Where are you?