My 2005 diesel tourer has been wandering about somewhat recently and - by rocking the top of the wheel vigorously with both hands while looking at the upper suspension arm balljoint (holding a torch in my mouth) - I discovered that the nearside upper suspension arm (wishbone) balljoint was flopping about in an extremely "sub-optimal" fashion. No need to jack up the car to do this test, as you can clearly see the balljoint between the top of the wheel and the wheel arch.
Earlier today I found it fairly easy to replace this entire arm without fully removing the strut, but you do need to remove the 5 strut top mounting nuts, force the strut downwards (by pushing it with your foot whilst standing looking at the top mounts under the bonnet) until the mounting bolts go down below the inner wing, then lever/pull the strut top mounting outwards about 3cm... you can then actually pull both upper arm pivot bolts inwards behind the coil spring and remove them from the bushes. I really don't see how this could be done otherwise (on my car, at least) and I did try for a while before I gave in and removed the strut top mounting! But, by doing it this way, I was unable to use a socket or even a ring spanner to undo the pivot bolts, luckily they weren't particularly tight so undid fine using an open spanner.
Steering stability seems completely back to normal now. Upper arm was only £27.50 from CarParts4Less (part of EuroCarParts), so a pretty cheap fix that took me less than 2 hours (I reckon it would have been 90 minutes if I hadn't tried to remove the bolts without removing the strut top mounting).
