I have a Electrolux Discovery Advantage upright and to access the power nozzle belt, just remove the 4 screws on the bottom of the power nozzle. Then, using a flat head screwdriver, pry off the "top" of the power nozzle at two points at the back near the inside of the wheels. (where the white and black parts of the housing meet). Remember, it's the top that comes off and not the bottom. To replace, just snap it back on. Make sure it snaps all around especially on the front. Replace the 4 screws.
Bill, October 2008