This is a good question. The ring on the EPS has been adjusted and I don't think this is the problem. It does 'feel' more like a rack issue than 'sticky' steering, and there is an audible clunk which I suspect is from the rack.
My local BMW Indy has suggested changing the rack. However, I'm tempted to see if it is the preload spring that could do with being adjusted/changed/cleaned alongside re-greasing the rack. That's a bit beyond me but I would be happy to travel if there is anyone with experience of adjusting the pre-load. A reconditioned rack is probably a last resort, and from what I can tell apart from servicing the pre-load they do very little else?
Other than that the car passed its MOT today with no advisories so it is well worth trying to sort out this particular issue. Always open to other thoughts, but reading through the various related posts the rack seems to be the place to start.