Tel: 0800 954 0154 dyson help line
I had a look on the www.dyson.co.uk site....
Click 'support' click 'Get expert help'
clicked last but one 'Using my Dyson product [Tips and manuals] select for yours and see near bottom left re unblocking it seems the base/foot plate over the brush roll is held by coin sizes slot screw undo and it's likely you remove the brush roll fit new belt on motor shaft and fit brush roll back through belt and pull hard to re-seat the brush roll ends. failing this ring them on their free help line as they ask you to do if you select change belt. Tel: 0800 954 0154
Bob, January 2009