I got an email back from The Williams re-build chap - Mark but it confuses me further!
See Below-
The track control arm is basically the bottom arm - and i would imagine its the bushes on the inner pivoting end you have heard about. Not come across those wearing out though, but the steering rack inner balljoints are something that wears out. You can buy the kits from renault - although due to their design are a real pain to remove, but even harder to fit correctly without the correct fitting tool.
Check the track rod ends first, then anti roll bar bushes in track control arm, then top strut ball race and rubber/metal top nut flange. A new modified flange is made now that sits on the strut mount area better. The ball race can dry out - making the steering less smooth to turn, but the power steering can mask this problem.
Im finding it hard to distinguish between the rod and the inner ball joint, did someone say the rods include the inner ball joints???