Honda-SOHC

Hi folks,
Been loving getting out in the sun on my CB550 
Noticed the rear sprocket was making a clunking sound occasionally and it looked as though there was a problem with the carrier. Close inspection (after dismantling) has shown that the sprocket carrier (flange) or where it fits onto the other part of the hub is worn as a previous owner has added a thin steel collar or sleeve which has broken up and is causing the clunking problem due to it being able to move slightly.
Would anyone know if wear on these parts this is a common problem ?
Is there a fix  or should i be looking for a new hub?
Any help would be appreciated.

if its a replacement i need ....anybody got one or can point me in the right direction?
oh and one more thing...
This..
http://www.gentlemansride.com/

Making progress on the Cb550 I purchased a few weeks back. The previous owner had begun to Cafe race it and fitted clipons and small indicators and there were some carb running issues that needed sorting. So Carbs off stripped and cleaned with new rebuild kits fitted. Indicators and fork ears purchased just need to fit. have removed the Marshall deeptone exhaust and fitted a stainless Motad system which went surprisingly very easy indeed! New stainless Hagon shocks fitted. Just need to fit the carbs and set them up.
Here's a pic of the exhaust and shocks fitted.

hello,
New Cb owner down in Bournemouth , said hello on the .net site and have been sent over here !
from the frame number the bike is an F3 according to the site info. is this correct frame number is
CB550F-2114450 . the previous owner has fitted clipons and was going to cafe race it but I  intentd on restoring it to more original style. was given a box of bits with original handlebars and rear indicators and have already purchased some nice shiny new honda mirrors, hagon stainless shocks and today a stainless motad exhaust a steal on ebay at £159 direct from motad .. As I'm not keen on the Marshall headers. will be selling on the clipons and have already listed a set of raask rearsets on ebay that were in the box they appear to be for a cb400. So lots to do, getting the carbs sonic bathed and set up and just need to find a grab rail and front indicators ( have already found the fork ears)
really looking forward to riding this bike it's going to be a keeper : )
hers some pics of it the day I got it.