So..... I 've had this sort of noise...like a bike with a primary chain which needs adjusting,only on the overrun or when going too slow for the gear I'm in.
Following a quick chat at the Festival of 10^3 bikes yesterday I have re-examined the oil pump/primary gear. Indeed the use-only-once castellated nut was not tight and the oil pump worm gear was not held firmly on the crank shaft, with a bit of looseness in the primary gear. This may also explain a partial seize earlier. Try as I might I cannot detect a spacer which should be between the primary gear and said oil pump worm gear either.Quelle horreur!
Well I have had a word with the idiot who took it all apart last year. He swears blind that there are no spare bits in the box and promises he will put it back together PROPERLY next time.
What's the best way to hold the primary gear whilst tightening the NEW nut if you have not got that special tool,last time I used a bar through the small ends.(Did I really say that?)