Hi, just done it myself using an inch and a half panel pin bent to 45 degrees a quarter of an inch from the head; to the l.h.side of the on/off button is a tiny slot; slide the panel pin (or bent terminal screwdriver) held in a pair of pliers down this slot about an inch and lever away from the cleaner body. This pushes in the clip on the side of the on/off button allowing it to pulled out. Then there's a single torque screw beneath (my third smallest allen key undid this a treat) which, when removed, allows the switch assembly to slide upwards and out.
Simon B
November 2008
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix vacuum cleaners.