First you have to take it apart...
I found that a Previous Owner (PO in Land-Rover speak) had
incorrectly assembled the steering box sometime in the past. This put
entirely too much pressure on the lower ball bearing assembly and one of
the little balls had split. This had seriously galled the race, and was
causing a lot of play in the steering which could not be adjusted out.
Here is a picture of it all put back together and ready for degreasing
and paint...