I would add to that answer two things: if it like mine, pop off the cover to the headlight to find the two screws, and remove the lightbulb to make sure you don't break it.
My powerhead would trip the thermal protector after about two seconds, and I thought perhaps the belt was hung up. Actually, it was just really dirty in there, and all the lint was apparently interferring with electrical contacts or bearings in the motor. A few puffs of compressed air to clean it out, and it is like new.
Chuck, October 2006