A balance control system comprises a motor, a transmission system providing connection between the motor and the door and adapted to move the door between a closed position and an open position located above the closed position, a counterbalance system to reduce power required to lift the door, an apparatus to generate first signal representing a force used to move the door from the closed position to the open position, and to generate a second signal representing a force used to move the door from the open position to the closed position, and a controller responsive to the first signal and to the second signal to indicate an imbalance of the door when a difference between the first signal and the second signal exceeds a predetermined threshold.