master cylinder brake issue help!!!!!

hi all
i have a 1980 s3 which has a girling 74660213 master cylinder the problem i am having is i cant get the second valve out at the back as i wish to over haul it .
i have a work shop manual but the cylinder it describes for disassembely is different than the girling if anybody can tell me how to get it out i woud be greatful

That part number appears to correspond to the later cylinder fitted to the 90. Might be something in the manual you can find here:-
pdf Land Rover Manuals | Landroverweb.com