just call the dyson warranty company....they should send you to some place to fix it for free. it just happened to me and i called and they called in a work order at my local vacuum place!
becca
October 2008
to access the switch & power cord, remove the dirt bin, where the dirt bin latches you will see (one) torx t15 screw, remove the screw, pop off the cover & you will have access to the switch & power cord. run a continuity check on both, if they are ok it could be the thermo protector in the motor, in that case you will have to replace the motor (good luck if that's it!!)
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Try fixfault.com to fix vacuum cleaners.