Huskyvacs, it is VERY MUCH POSSIBLE for the powerhead socket on the Shark Navigator body to burn out - in fact, it is a known flaw with them. I always tell anyone who has one, to NOT use the lift away feature, just use it as a normal upright, and they won't have the problem of the receptacle burning out. What causes the problem is the latch on the side wearing down over time with use, and it eventually allows the powerhead neck and main body to have enough play between them that it causes arcing and burns out the receptacle.
Also, it is the powerhead receptacle that turns on and off, NOT the powerhead. When the power switch in on I position, it only sends power to the suction motor since the brushroll isn't needed in bare floor mode. It's only when you put the power switch in II position that it sends power to the powerhead to turn on so you can clean carpeting.