Forget the Dyson site - the usual disclaimer about competent electricians, hence cannot give advice etc.
Advice below is how I did it - but be careful as the bits are held on by flimsy clips that break all too easily (sums up my DC03 experience - will not be buying another).
As in my case the cable sheath had split just at the cable entry point, I just shortened the flex and refitted. It was too damned short to start with, so little loss in convenience, as still have to use an extension lead.
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April 2006