How do you change the bulb on a discovery td5 mileage clock?

To change the bulb on a Discovery TD5 mileage clock, first, disconnect the vehicle's battery to ensure safety. Remove the instrument cluster by unscrewing it from the dashboard and gently pulling it out. Locate the bulb socket on the back of the mileage clock, twist it counterclockwise to remove it, and replace the old bulb with a new one. Finally, reassemble the cluster and reconnect the battery.