Ok, I need to correct myself, my previous post concerning the adjustor and sector shaft preload was WRONG WRONG WRONG. Sorry.

After looking at the steering box I have that's in pieces, the adjuster 'does' adjust gear lash between the sector shaft and the ball-nut. It does this by the gear shape and the overlap betwen the two axis of the steering column and the sector shaft. The preload on the sector shaft is determine by the spacing in the washer mechanism at the top that connects to the adjuster square driver that you can see on the top side of the steering box.

The adjustment though, is fruitless if the bottom sector shaft bearings are worn.

I really think these bearings are the cause of much of the trouble we have with steering boxes. Especially when there is a lot of play when changing direction from side to side.

Cheers,
Chris