Vacuum Cleaners Discussions

In regards to the power nozzle on the Perfect Canister, what I'm finding with it compared to the Lux PN5, or any Lux, is that the Perfect is much noisier?? At first I thought there wasn't enough tension on the belt, so I adjusted that, it made it worse. So, back off on the tension. Tried a different belt, no luck. Tried a different brush roll, Lux and Cleveland Woods brush, no luck. As long as the brush is not contacting the carpet, it runs smoothly, but as soon as it touches, especially low pile, and on the back stroke, it sounds like Tony The Tiger roaring. It rattles.  The brush roll is locked into place. Have others encountered this same issue??