You are luck, as this is the easiest repair on the truck. Just pull off the center knob, and you will see the tiny bulb (it uses a low-tech fiber optic system, a piece of clear plastic that directs light to the other two knobs). The bulb just pulls straight out. You will need a tiny pair of pliers, or a pair of tweezers to do it. Bulb can be found at any chain auto parts store, no need to go to MB for it like the "exotic" dash bulbs which are used in other spots on the truck.