Well , I said I'd report back !
Not good news , the blue smoke on cold startup is still there . It probably never went away ; perhaps I just wasn't seeing it
So now I have to assume it is indeed valve stem oil seals , and decide whether to live with it or go for what will be an enormous strip-down just to replace 24 little bits of rubber
I doubt I will be able to live with it as I like things to be A1
Maybe I will wait till the spring now …...
