Just one little addition to JB's answer to avoid breaking the plastic: after pulling off the rubber siding, take a small flathead screwdriver, insert it in the the small opening at the filter end, push the screwdriver just a little bit further in the opening, this will unclip the rigid plastic siding. With the vaccum filter end facing towards you, using needlenose pliers, pull the rigid plastic siding so it slides all the way along the vacuum.
Fred and Sylvie, June 2006