s52 engine

[moggie]

hi guys,ive changed the solenoid and piston seals on my twin vanos unit but still getting a slight oil leak which seems to be coming from the back of the vanos unit,i did get a large o ring with the kit which i havent fitted as there was no instructions on were it went,im guesing it goes behind the vanos unit?could it be this that is leaking and is it easy to change.or could it be the rocker cover gasket.thanks for any ideas.