Is there anything on the column ie a bush or the column itself that would wear and cause a judder under braking?!

Basically the gfs mk4 cab has had abad judder for ages, ive now changed/checked pretty much everything including another rack with new rod ends and its better than it was before but theres still something there under braking.

The reason i ask bout the column is when its in the air if u try and turn the wheel by hand you get a 'clonk' coming from the steering, you have to give it a forceful push to get it to do it, and its the same with either rack so cant be that.

So is there anything that can wear down the column that could cause a vibration/judder?! If theres play anywhere from the wheel down to the rack obviously under braking your going to get movement which could obviously be causing the vibration.

Cheers

Tony