Steering box - top end wear

[Chris Ivin]

I have a steering box that I am planning to exchange for my existing worn box. The only play in the new box appears to be at the top end with about a sixth a turn of rotational play. The person I bought the box from said that he had taken the horizontal play out through the shims and new ball bearings but could not improve the rotational play anymore. Is the remaining wear likley to be mainly in the worm or in the nut:?: