I have a Kenmore Whispertone 12.0 amp canist type vacuum claener. The model number is 116.26519690. A rear wheel has come off. It looks like some kind of wedge pushes into the stem that gos into the body of the main vacuum unit. I can only find 2 screws under the bag lid and can't get the moter cover off to look for the thing that holds the wheel on or in.