how do i change the brushes for hotpoint wm54p? and what size is required?

i have a hotpoint wm54p and it has a smell of burning coming from it. the motor is making a strange deep droaning noise. the spin cycle is not completing and labours whilst trying to. plumbing has been checked and no blockages/bends/leaks. could it possibly be brushes that are required? or possibly the motor/drum or worse. if brushes are required. then which ones do i purchase?