I've also got exactly the same problem with my DC20, and like the original poster can't work out how to get into it to get under the on/off switch and see if I can fix it. I've managed to remove 2 star screws (using a flathead screwdriver) from under the washable filter, however this does not seem to release the top half of the machine which has a join around and looks/feels like it should be removable. Does anyone know how to get into this DC20 animal?!!