Hello, I had the same problem too. I did find the answer though. You have to turn the vacuum so the bottom is showing, and on the left and right there are short plastic tabs on the outside edge, that are tabs from the top cover. If you take a flathead screwdriver, and push thos towards the outside, the whole top of the vac will come off, and you can replace the belt very easily, and the top just snaps back on.
Jim, February 2005