have your turned off the brush control on the Right hand side of the cleaning head?
Andy M
February 2009
If your DC04 has a clutch unit there are two belts. One is the motor>clutch drive belt, the other is the clutch>brushbar belt. The motor belt is available separately, and in theory replaceable. The other belt is assembled together with the clutch into one assembly. It's available from eg. 'eSpares' for around £20. Good luck getting the clutch unit out of the head casing. I can't fathom it!
AndyH
February 2009
dysonmedic.com
has really nice pictures and some text under Belt Change
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix vacuum cleaners.