Leaning more to a seal leaking, I've noticed the left side of the engine is always wet, but I haven't been able to pinpoint where from. Looking at the guide to replace the seals in situ, I shouldn't need to adjust the metering if I mark the FIP accurately.Might be FIP timing. Also worth checking the lift pump is chucking out fuel as per Wammers post in the Technical Archive.
Alternatively, I have some PRC1440B2 that I accidentally dropped into my bag one day while at work. I could always slap a load of that around the joints in the FIP (or wherever I can find the leak coming from) and see what happens.