Do you know if it has the servotronic option? Its possible that it is out. If you dont know what servotronic is...there is a variable valve in the steering box that is fed by the car speed signal. At low speeds it gives the power steering a boost by opening the valve more. At higher speeds the valve closes and there is no power steering boost. When it goes out, you get no power steering boost at all and your steering seems difficult at low speeds.