I have the same problem. I had zero volts on the brush head supply terminals and have cleaned and tensioned the connectors but still no power. When the brush head is connected and I pull the trigger the vacuum starts then stops then starts again and continues with suction but the brush hasn't moved. When I pull the trigger without the brush connected the vacuum starts with no stop and start again. Could this indicate a sensor stopping the power for some reason? After assuming the power to the brush wasn't being given for some reason I manually rotated the brush and found it a little stiff even though there was no hair or the like tangled in it. I tried the power again and noticed it moved slightly then stopping again. I repeated a few times and it has started to work again. I am now of the opinion that the power isn't supplied if the brush head motor is too stiff due to a fault or tangle, so after cleaning all electrical connections try loosening the resistance of the brush motor by giving it a few turns....