Steering related 'knock'

["Mike Stevenson" <mike.stevenson@domain.elided>]

Fellow listers,

If I turn my steering wheel to the left, after half a turn I get a 'knock'
at the front end on the left.  It happens whether I am stationary or moving
slowly but, due to road noise, I don't know if it happens at speed.

I've checked the steering and suspension components externally for obvious
causes but can find nothing.  The best way I can describe the noise is that
it's akin to a shaft being turned in a bush that is offering resistance and
then it suddenly 'gives' . I hope that makes sense.  Is it possible for the
front damper upper swivel assembly to bind up and suddenly release.  I'd be
grateful for your thoughts.

Regards
Mike Stevenson
ps I've been away for a while, it's good to be back!!