Re: powersteering trouble
More than likely the box.
But..... also check the pitman arm and idler arm angles. With the front wheels pointing straight ahead, the pitman arm and idler arm should also be straight ahead. I have had a wheel aligner shorter up one side tierod and lengthen the other, which changed the operating angles of the pitman arm and idler arm in relation to the centrelink. Made one direction easy, and the other hard. Also limited maximum lock on one side as well.