YouTube has a video of changing washing machine brushes.
Brushes are little blocks of carbon (often in plastic holders), spring loaded and held stationary delivering electrical power to the rotating part of the motor. Like a pencil they wear out over time.
Access to the motor is from the rear of the machine
http://www.youtube.com/watch?v=0GmtRBiXLFc
Peccavi, August 2009