Dyson DC04 Zorbster makes a loud, ratchety noise?

When I try to use my Dyson DC04 Zorbster it works fine until I tilt it to use the beater bar then there is a very loud, plastic ratchety noise. I looked around the internet and decided the clutch must be at fault. I have replaced the clutch with 2 new belts also. I have oiled the axle of the beater bar and that runs fine too. Unfortunately I still get the horrible noise when the beater bar is running so what is the problem?

Andy
March 2011