1) Lift the Latch handle to open the Lid.  2) Hold the canister lid in the palm of your hand with the underside facing upwards. With the other hand, push out the Degassing valve from the center of the Lid to detach, together with the calender wheels 3) To replace the valve, close the lid, and insert the outer Calendar wheel into the top of the canister. Next insert the degassing valve, with the metal side facing upwards. 4) Insert the Month tracker, covering the Degassing Valve, and pressing firmly to secure.