I have the same problem. After a few days it stops fluttering. I get a replacement and it happens again. This is my third device that stops working after a few days of use. Currently i requested replacement from Monaghan. They will send a new one. I need to try to use a different disinfecting method. I have been using the microwave with the steam bag. Maybe the white thin valve gets overheated in these newest devices. I used my very first device for 6 months with the same cleaning method.