11years+ old likely time to retire it,  what length is it Eye to Eye and Stroke hope it's a standard size,  doubt they'll have seals to fit it available these days,  look up tftuned though give them a e-mail just incase.

Its 160mm i2i and have tried TF as recommended by my brother but no joy. Will look now for a 2nd hand newer model of shock or I can have it reconditioned by Wind Wave the Marzocchi Importer for £55 which seems to be the best option at present.

Shock technologys improved alot in the last 11-12 years,  you could pick up a RS Ario Air shock with spares available for £100 ish,  much better damping,  unless you want to keep it original ofcourse.