Hi Tony,
Thank you for bringing this to our attention. We apologize for the inconvenience and are sorry to hear that the knob has fallen off again. We will make sure to address this design flaw and work towards a solution. We appreciate your feedback and thank you for giving us the chance to replace it for you quickly. If you have any further issues, please don't hesitate to reach out to us. Thank you for choosing our product.
Best,
Aventon.