As a former DQ franchisee with three locations I refrained from attempting to train teens how to properly disassemble, clean and reassemble what are, arguably, the heart of your profit making. Since I couldn’t be at three stores at once I trained my adult managers to be in charge of cleaning and maintaining the soft serve machines daily to ensure proper product temperature and overrun. At closing teens would empty the machines and then run a warm bleach based sterilized solution into the machine all night to inhibit the growth of bacteria in the closed system. A poor bacteria count from the milk inspector during an unannounced inspection could shut you down for days resulting in a fine and degradation of your reputation. Again, too much invested to leave to the whims of a teenager.