Just used this answer to fix our aging DC04 Zorbster with the same issue. I cut a bit off a business card and wedged it in the switch - works like new again.
I should point out my wife had taken it to an appliance repair "specialist" not once but twice, and they failed to fix it.
Andrew Strachan, if you ever read this - thanks :)
Newless Cloob
November 2011