There’s some play, and a clunk when the wheel unweighted, from the top bush on my shock. The pin that runs through can be wiggled slightly, so what is the most likely cause of this- do the ally bushes actually wear and need replacing? Seems a bit odd because the holes don’t seem ovalised, there’s fairly equal play in all directions.

Wear in either the shock eyelet bush or the mounting hardwear top hats.
Try just replacing the bush and see how it is then?

sound slike the du is worn.

its a little bush that sits between the shock body and the alu/steel/ti reducers.

get some of these
http://www.ebay.co.uk/itm/4-X-Performance-Polymer-Shock-Bushings-DU-Eyelet-Bushes-Fox-Rockshox-Marzocchi-/271215629680?pt=UK_sportsleisure_cycling_bikeparts_SR&hash=item3f25b61570

and ask the lbs to fit them for you.

Yes, the ally bushes are designed to wear (and the shock bushing)before your shock eyelet. Have you checked that the shock bolt is torqued up ? If not, the bolt can move in the ally bushes (top-hats), giving a bit of play as the bolt should clamp tight against the top-hats. This is so that the shock bushing moves in rotation inside the top hats. Hope thats clear !