If your Plum will go unused for more than 60 days, you should prepare your Plum by first running a cleaning cycle on both chambers. This is done by going into Settings > General > Clean.
After completing the cleaning cycle, open the door (Settings > General > Open Door), clean the sealing cups and dry out any condensation under the needle doors. Proceed to leave the door open and power off your Plum for 24 hours to let any condensation dry. Lastly, close the door and store in a cool, dry place.