Open the doors by pressing the release button. Lift the blue locking levers. Take the keg with the assembled tap unit out of the appliance. Remove the tap unit from the keg by pressing the release buttons on both sides of the tap unit. The tap unit will be released from the keg with a click and you can remove it.
You have to remove the tap unit from the keg before you can replace the tube. Hold the tap unit over a sink. Press the release button to release the tube. Pull the tube connector out of the tap unit and remove the flexible tube out of the tap body.
Clean the tap unit with hot water. Assemble the tap unit onto a new keg and insert a new tube into the tap unit. Make sure there is no frost on the inside of the appliance. Place the new keg into the appliance.