I just got a new Medela Swing breastpump and I don't understand the cleaning instructions. It says to wash all parts that come into contact with the breast/milk and lists only the breastshield, valve, membrane, bottles, and caps. It says to wipe down the the motor and pump body with a damp (not wet) cloth if necessary. But doesn't the milk run right through the pump body?? That's the part that you connect the breastshield to on one end and the valve on the other. I keep looking at it and I can't see how the milk would not go through there?