Hi and thanks for the replies.
1) No not done anything at the back.
2) Replaced with pattern part although tried cleaning the orig 1st with similar results ie light went out then came back on again.

Just thinking, do the sensors pick up from the bearing and if so can it be dirt and how do you clean them? I am more used to gear type of abs ring.
Think I may try cleaning all the sensors starting with fronts.Is there a test for the sensors using a multi meter?
Thanks again Barrie.