The earlier boxes should be adjusted at extreme lock, to avoid stiffness at any point in the travel. Wear mostly occurs around the centre position so the box develops more play around this point, but manufactured clearance was the same throughout the range. There are three keyways in the gear so that a new third of the circumference can be put into use when wear (play) becomes serious.
The late Ruby 'hourglass' type box does not have the keyway options because it uses a sector intead of a complete gear, but in this application it is manufactured with some clearance towards the ends of travel and no clearance at the centre position. Adjustment must be made in the centre straight ahead position, and play at the ends of travel is to be expected.
In both boxes adjustment should be taken only to the point where the wheel is free to turn through its whole range from lock to lock.

Robert Leigh

Location: just north of Cambridge

Location: Auckland NZ

Here's the official Austin advice reproduced on the Cornwall A7C site http://www.austin7.org/Austin%20Seven%20Journal/Overhauling%20Steering/

Location: Isle of Wight

Except we are talking here about Hourglass steering boxes, so the cornwall site info is not entirely relevant.

I have just looked up what Woodrow has to say, anyone who follows the advice contained there should not have any problems. Unless that is the worm and selector are worn so badly that replacement is the best option.

Location: Auckland NZ