Power steering not self centering

[Chris-M]

My daughter has just passed her driving test and is driving our 2009 IQ2 which had been SORN’d in the garage for 3 months.

The steering seems a bit sticky and isn’t self-centering well. If you adjust the angle of the steering column, it can make a short term improvement to the stickiness. 
I sprayed down the steering column with WD40,which helped the wheel turn a bit. The car has brand new tyres and today had wheel alignment done (small adjustment was needed). The steering is a bit better but self centering still not great. I’ve done a visual inspection on the suspension arms and all looks fine.

I’d be grateful for any advice on the following:

1. Do IQs normally have good self-centering? It’s amazing how quickly you forget after driving a newer car

2. Is there a bearing or bushing on the steering column that could get gummed up and provide resistance to steering column turning?
3. If there is a problem with the steering, how could I determine if it’s an issue with the steering column, electric power steering motor or the steering rack. I don’t want to just start replacing components, as that could work out expensive and not fix the issue

All help greatly appreciated.

[Chris-M]

And the Battery is fairly new and fully charged