Notchy steering

can't figure this one out my D1 200tdi has HD steeering arms and a known good Terrafirma steering damper with a relocation kit so it fits on the front steering arm. Now the problem if I want to turn a corner then I have to be ready to randomly fight it to turn it's as though something is sticking but only at one point of the turn so it'll steer fine then randomly feel as though the power steering has died then when I give it a bit more to turn the required amount I'll suddenly be steering too far and have to straighten up which I will then feel the same sticky point.
I think I read something here about a wheel bearing or cv joint causing something similar to this but I can't seem to find it again :doh:
Visually all the steering system is fine, fluid is on max arms are straight damper is good track rod ends are good and have grease in them (greaseable). the only problem I know I have it the steering wheel moves in and out of the colomn by a few mm but I have moved this about and it doesn't affect this problem.
can anyone help with this as it is effecting the drive and don't want it to get any worse as it could end up being dangerous.
anyone know how to sort the steering wheel movement aswell

cheers in advance people

Try loosening the adjuster screw slightly on top of the steering box I over tightened mine and it felt notchy

check the linkage ujs, drop drop arm and feel wheels lock to lock

As per Jamesmartin, there are are two U/j's on the steering column that can go dry and sticky.

Get some spray-on grease and lubricate the U/j's and you may find that cures the problem.

Cheers people all things I can check while at work then ill report back after the drive home

Remembered to spray the uj's yesterday and the steering feels better so may even remove the uj's to clean them properly. Cheers for the advice people