[Closed] what causes fork top out clunk ?

Have recently serviced both mine & the missus Sid forks and apart from having an absolute nightmare to get the shaft bolts to break the lowers free the service went well so well I decided the missus would be better off with a bit more travel so I got her a 120mm travel air shaft. I had the usual mother of all battles to get the lowers free again in which I had to bash the rebound side bolt so much the allen key was starting to drive through the bolt splitting a bit before the lowers would come off. Anyway I fitted the new shaft but now the fork rebounds with a massive clunk. I have tried playing with the rebound and pressures but it just returns with the massive clunk no matter what I do.

Any ideas folk's ?