I disconnected the downdraft exhaust pipe and unplugged the stove. I lifted up the stove and rested, supported it over the opening with a few pieces of scrap lumber. Opening the stove, I found all 4 switches dirty. After disconnecting one-at-a-time, I found the faulty switch. Shopping for a replacement, I noticed a parts diagram showing grommets around the knobs. My stove was missing all the grommets, allowing debris to gunk up the switches. Since switches are expensive, I cleaned mine in a bath of rubbing alcohol, let them dry out, and then sprayed them liberally with DeOxit (an electronics cleaner). That fixed the immediate problem. I ordered the grommets and reassembled the stove. The grommets arrived in a few days, and installation took under 5 minutes.J