sounds like someone put the pitman arm on a notch or 2 off center. You can check this by counting the number of turns from center to full left and full right. If its off one way will turn more. If so all you have to do is pull the arm, reposition and re-align. If it is off center it will cause the power steering to try to constantly correct itself back to center.
hope this makes some sence to you.
95 E34 530I V2.37
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Those who make peaceful revolution impossible will make violent revolution inevitable.
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