Power Assisted Steering feels heavy at idle.

[Auto Addict]

Hi all
I've had this PAS issue on my 2009 XC60 D5 AWD Manual for a few months now and it manifests itself as PAS feeling heavy but only at idle... I can not stress enough this is only evident at idle and not always either. For example... on morning cold start ups the PAS feels fine, even at idle (most likely due to higher idle RPM ) to when it's fully warmed up. Otherwise the PAS is perfectly fine 95% of the time. There are no leaks or untoward noises from the PAS system neither. When fully warmed up I have to gently rise the RPM to around 900-1000 for the PAS system to be active.

Things I've done so far to cure this PAS issue are:

- Full PAS fluid flash / refill (twice) with 2 litres of fresh CHF11S (the old fluid was dark brown) every time. Fluid is now perfect & fresh.
- Brand new "Genuine" Volvo PAS reservoir / fluid bottle (the filter inside the old original reservoir looked a bit mucky)
- Brand new "Gates" Aux belt (even though my XC had the official recall few years ago) ... it was due for another change anyway.
- Brand new "OEM / DAYCO" Aux belt tensioner (even though my XC had the official recall few years ago)... again like the AUX belt it was due for a change anyway.

I've done a search on here but to no avail... I'm wondering if this is an early indicator of PAS pump failure and/or PAS pipes degrading internally.
Any further thought / advise before I'm forced to play "Parts Lottery" would be most appreciated.
Thanks in advance.