An imaging system for a printer utilizing a friction belt drum drive is comprised of a drum position sensor, drum pulley, drive belt, motor pulley, drive motor, drive motor position sensor, and controller. The velocities of the drum and motor drive pulleys are measured using the controller and position sensors. These velocities along with the drive ratio are used to determine and monitor slip between the belt and pulleys. The magnitude of the slip measured can be used to trigger the controller to respond to the slip event. These responses may include, for example, disabling the motor or reducing motor current or providing a warning indicative of an excessive slip event. Slip measurement combined with other measurements such as motor current can be used to determine the torque capacity of the friction drive. Further, long-term changes in the ratio of pulley velocities can be used to determine drive belt wear.