How do I open the canister so I can change the motor. I have taken 4 screws off and cannot find what else to do for opening it. A repair man told me the motor was caput and Sears do not do repairs anymore so I purchased a $100+ motor and wil change it myself, But I have to figure out how to open the canister beyond the 4 screws I have removed . . . . I can slightly pry the 2 main parts off but there seems to be something else I have to undo or unscrew . . . what is it ?