The O-rings on your Norwalk are FDA approved and must be removed and cleaned at the end of your juicing day.
To remove the O-ring, take a soft instrument, such as a toothpick, to lift the O-ring from the face plate. Wash thoroughly in cold, soapy water. Do not store the O-ring on the face plate of the Norwalk for long periods of time, as it will become brittle and break. After placing the O-ring back on the face plate, be sure to add a drop of olive oil to the O-ring, so that the feed tube slides on easily.