There are a number of reasons why the whisks may not be spinning. This can be evident by no movement of the milk in your Aeroccino, or a whisk that comes loose from the inside of the unit. To ensure your Aeroccino whisks are working sufficiently, please conduct this test: 1. Place the cappuccino (or frothing) whisk into your Aeroccino. 2. Fill with cold water until the water covers the whisk. 3. Press the button to start the Aeroccino and ensure the light shines red. 4. Check to see whether the water is spinning in a whirlpool formation and is heating. If you have any further questions about your Aeroccino, you can contact Nespresso directly via our toll free number 1800 623 033 (toll-free, seven days a week).