I'm planning on renewing the oil and main filter in my haldex 3 unit.
There's plenty of threads showing that and the kits available include oil, filter and cap/screws.

However, should the pump be removed and the small filter be changed also or at least cleaned? Can these pump filters and associated o-rings be bought? Or

Or is a basic oil and filter change all that's required? The car is functioning correctly and the oil is about 4 years old and has covered less than 20k miles in that time... (Since land rover themselves completely fitted a new Haldex unit)

The small filter on my one (Gen 4) was all gummed up. It’s a fine plastic mesh filter and just needs a rinse out. Past: FL2 TD4 HSE Auto
Evoque SD4 Dynamic Lux Auto
Present: Audi A3 S Line.

Is it necessary to renew the o-rings on the pump? Anything special or will a standard rubber o-ring do?

Apart from the one main large O ring that goes between the Haldex unit and housing, I didn’t replace any other seals. Past: FL2 TD4 HSE Auto
Evoque SD4 Dynamic Lux Auto
Present: Audi A3 S Line.

The o rings are available if you need them. From memory I don't think you can remove the Gen 3 pump without removing the drive coupling first though. (Now Sold). 2008 Freelander 2 (Nazca Sand) SE TD4 Auto. Statutory write off & on WOVR for hail damage but still road legal.
171037Km as of 09/05/22
Superchips Bluefin Flash
Nanocom Evo II (also sold)