I am having the same problem and went to a 'Pay for the solution' kind of website which is where the following information comes from.
Evidently, a known problem with Hoover carpet cleaners is the brush-spin speed setting switch. Replacing this item will fix the problem.
In my case, the brushes would turn but could be stopped with the slightest of pressure. The problem was the same with either fast or slow setting selected, however, with the 'off' position selected the brushes would stop turning, as they should.
A replacement switch assembly is actively being sought as we speak and I'll report back later with the outcome.
Hope this helps.
marcustandy, July 2008