This is the main on/off switch for the all Dyson DC-07 and DC-14 Upright models. It is replaced by unscrewing a single star bit screw above where the dust bin attaches to the vacuum cleaner. If your Dyson has all of a sudden stopped turning on, this is a very common problem, and should be one of the first parts you should check.
Filed under Dyson Carpet Cleaners by bestcarpets