...I hope this isn't oil related trouble after all...
...the little sockets under each of the hydraulic units are 3mm thick - so in principle I could get the thicker ones but I don't think that's necessarily gonna help me as the hydraulic units look like they only protrude by 1.9mm (measured)
I think I have to re-fit and then crank the engine over to see if oil fills these little buggers or not before I start trying to spend my way out of this!