Well, seems I have the same diagnosis, at last. All of the oil drillings on the exhaust side of the cylinder head are poorly aligned, and 2 completely miss the oil groove in the cam follower altogether. Inlet drilling are in perfect alignment. This will come as some relief to those of you who are fed up having to ask me if it's fixed yet......Time to get the Dremel out.
Maybe in the future cylinder head machining in China will better than Brum.(Virtually brand new cylinder head, but I won't let on who I bought it from 😳)
Malcolm