Dyson dc07 animal it does not suck very well?

Hi can any one help me please, a good few months ago I got back my dc07 (old shaped one) from John Lewis as the motor had burned out. They let me lend a brand new one while mine was getting fixed. The one they lent me was so powerful, got mine back c**p. You have to go over a section of carpet about 3 times just to pick the bits up. I bought brand new filters and cleaned the brush bar. Still no joy, so my question is how do I dismantle the cyclone to give it a good clean out. I have took the 3 screws of the top out but it still wont open. Any ideas please. Thanks Tony

Tony Schorah
September 2005