Evening all,
Went back to ECP with the faulty tension bolt / seal and swapped for a new one, activated and tightened to 75 Nm and the new seal is not passing.
Cleaned old oil as best as possible from behind the engine where the old tension bolt seal failed.
Thanks to everyone for your input, you were most helpful. Still have the occasional squeal from the aux belt, normally first start up or damp conditions which normally clears after a few spins. will stick with it for a week or two and if necessary replace the belt if problem doesn't go.
Thanks again 🙂