it sounds like the carbon brushes have worn in the motor, remove the old brushes & check them because there are 2 types that fit your model, click on the link below to see both types & you can purchase them through this site aswell.
http://www.candmdomesticappliances.co.uk/search.php?xSearch=wma56
www.candmdomesticappliances.co.uk, December 2009