This happened to me with my first range rover (a 1979) and it was a collapsed swivel bearing. I'd driven back from Wales wondering why the steering was even more vague than usual! Replaced both swivel bearings and all seals and it was fine again - just a bit fiddly getting the pre-load right with the shims but worth doing properly.

stripped him down & the top swivel bearing had broken up & all was left was the inner
the bottom was not much better & fell appart as i removed it !
new bits ordered & thanks for the sound advice once again !