Noisy vacuum cleaner

[Lumihum]

I have a Samsung upright vacuum cleaner, and it makes a terribly loud high pitched noise when I switch it on, it never used to, I have taken it to bits and cleaned it all, checked for blockages etc, but it still does it. Do I need to change the belt maybe or is there something more sinister wrong with it? Many thanks for any suggestions

[scoobysoo]

Mine makes that noise when there is too much hair wrapped around the long brush head.