the flex is connected to the on/off swich ,if your power swich is mounted on the handle ,look to the rear of the handle you will see either two screws holding the back section to the handle or one screw holding the entire handle in place .your aim in both cases is to gain access behind the power swich to renew and re route new flex .you will need a basic crimping tool and of course two new connectors,usually the spade type ,do not be tempted to cut and tape the new flex in although the handle is made of plastic and well insulated poor and unsecured wiring can be a disaster waiting to happen .if you don't feel confident I would suggest taking vac in for repair ,.
mech monster, October 2011