There’s no longer such a thing as a Sonnax valve body assembly. I would suggest that you send your worn unit to someone like Valve Bodies UK http://www.valvebodyuk.co.uk/ or STA Aylesbury https://www.staautogearbox.co.uk/ who own a Hydra-Test...

Phil. Many thanks. Got around to doing this and all now sorted. 2hrs of work including taking of and on. Thanks again.