eBay sellers hey?
I have been doing a lot of research on this issue and it was ither service the run down freehub or look for an replacement.
Apparently the freehub spingery used back in the days was the ultegra 6402:
However, from what i can gather these parts are hard to find and buy these days, but there is an alternative which the FH-M750 can do the same jon (granted this is a 9 speed freefub) people have done this before and it works perfectly apparently.
This is also hard to find at times, but the parts number is the same in the FH-M760 so I've ordered that and hopefully this will sort the issue from my side: