HOW DO I CHANGE THE BELT IN A DYSON 07?

I have the same vaccuum cleaner where the drive belt for the brush has broken. I have taken the thing apart and found that to change the main drive belt would be straightforward but to change the brush belt, special tools and knowledge are required. To get at the belt, the whole assembly needs to be removed and I cannot find a way of doing that without breaking the thing.
If anyone knows how to remove the blue knob that engages and disengages the brush, then it should be a repair that can be carried out by the user.
I have been told that it is a "specialist" task by our local repair shop and that it will cost around £45.00 to repair. Expensive but probably worth it to save breaking anything else.

Hopefully of some help

Regards,
Neil

Neil Broughton
May 2005