So, stripped the haldex including the basket with all the plates in.
Cleaned the pump and filter.
fitted a new filter.
stuck it back on.
Put .65litres of haldex oil in it as per the handbook.
Put the 15amp fuse back in.
Done about 20 full lock reverse turns in the car. Which is when it used to make a bad noise and scrabble.
Silent, with no scrabbling for now. I am however aware that people say it can come back after about 25 miles driving.
If it comes back at least I will know it is the accumulator knackered, and I can consider the scrabble fix.