1999 Mercedes Benz CL500 cl600 pump

I am experiencing a really loud whine when I turn on my car and turn the wheels. It happens around 90% of the time, quiets down after a while but never fully goes away. I can feel it in the steering wheel when i turn but there is no loss of assist. The fluid levels are fine, it was a little low but not alarmingly so. I know there is a small, r4ally small leak coming from the steering box, so my question is this, do I change the pump, the box or both. Knowing the costs which should I try fiirst. Also when I turn the car on, once in a while the steering wheel will jerk a littl and this never happened before. But as I said all this is intermittant Otherwise this car rides and looks like its new and I love it.

Thank you
Pete