i had the same problem but with the hoover apollo supreme, it was the fan blades near the air intake that is causing my grief.
The blades sort of creep nearer and nearer to the casing causing the loud metal screeching noise as the blades hit. I took a hammer to it and pushed the blades further back on it's axle. Stopped the noise completely.
They don't really secure it properly, it just a silly wire spring clasp that holds the fan blades onto the axle of the motor. piff!
ken
March 2007