do you have a cable from the helm to the brazil valve (brazil valve hooks to the arm inside the transom on the outdrive assy. If that is it, I suspect you have a loose gymbal. Try grabbing the outdrive and see if you can move it side to side and up and down.
If you have a full hyd system (hoses going from the helm to the hyd cylinders) then you probably have some dirt or debris in the system - try cleaning the in line filter....