HI
Alan, where did all that sludge come from ???
I now remember something similar happening on a Triumph brought to me some years ago
Jeremy,
A collapsing oil pipe when it gets hot on the suction side is worth a thought????
On the other hand
Why not set up a reverse flow into the engine???
Weird ???
Ok add a T into the feed line to the oil pressure gauge, a pipe from the tee to a pressurised oil feed
maybe one of those pressureised brake bleeding bottles??? or similar
block off the feed from the oil tank
remove the timing cover and block the feed to the block in the outer case, since the crank is holding pressure
remove the ball from behind the oil pump to allow the pump to be pressurised, refit pump
remove sumpplate
pressurise the system
You can pressurise the timing cover block separately if needed
now you can watch where the oil pees out,
HTH
John