Vacuim sweeper motor has a high pitch squeal otherwise runs fine

If you can notice a smell of burned rubber near the sweeper, then you most likely have a slightly stretched belt. The belt would be spinning against the beater brush, causing the squeaking noise -- as it heats up, the belt will begin to smoke, or at least give off the smell of burned rubber. This will be the most noticeable if you use the vacuum for a few minutes and then turn it off -- most times the suction from the vacuum will pull the smell into the vacuum and keep you from noticing it until it has been going on for quite some time. Replacing the belt should fix the problem.
Before going out and buying the belt, you might want to check between the belt and the beater brush -- if there is a lot of debris between the belt and the beater brush, it will cause the same type of slipping as a stretched belt, and could also be the cause of your problem. Either way, to fix the issue, you have to open the bottom of the vacuum and take a look at the belt -- if it looks to be in good shape, move it around a little. If it has a lot of room to move, it's probably stretched. If you notice a big hair clog under the belt, this is most likely to be your problem -- clean that out and you should be good to go.