The power steering control valve needs to be aligned so that the pin that goes thru the control valve housing and the hole thru the end of the drag link. If that pin is not installed, the control valve can turn and start rubbing against your sector arm.
Also, make sure all four of your hoses from the control vavle are not binding or rubbing against something when you turn the wheel. Need one guy sitting in the car turning both ways while you watch the hoses as they move. It is a mistake not to install the hose bracket that mounts on the inside frame rail.