Not having dealt with anything so modern I was cleaning the reluctor ring on the front drive shaft, through the sensor hole and the ring had a lot of grease between the segments and I wondered if they should be clean or should expect to have some grease around them?
Many thanks for all the help so far.
David

My reluctor rings were dry with no grease or oil on them.

Not especially grubby either given that things had been undisturbed long enough for the sensors to become solidly fixed in place. Which is not normal. They may be very tight but the sensors should come out.

Odds are my reluctors etc were as originally assembled so were still dry after 18 years and 90,000 ish miles.

Looks like you are loosing grease / oil from somewhere.

Clive