We had to completely disassemble. Take the two huge bolts out of the handle (they screw into the accessory rack which needs to be removed as well). Then unscrew the back and you'll find your heater inside.
Hope that was enough info. Kinda hard to describe. Basically unscrew everything from where the handle connects to the storage rack and then you will be able to see how to get the back off to get at the heater.
Danni (and her Dad... mostly Dad)
December 2007