Any idea why the steering wouldnt return to the centre?

 

umm....not sure if it could be a steering rack....

 

Is there a way to adjust the amount amount of steering pressure/ steering assist from the pump?

 

I don't think so, but I suppose the pump could be bad?

it couldn't hurt to change the fluid

 

I think you're on the right track by checking the PS pump and rack. check your rack for leaks VERY carefully (hoses, fittings, the "boots" on the ends, eveywhere). some shops flush power steering systems - maybe give that a shot, but keep in mind you'll wind up re-flushing the system if you get your rack replaced.

keep us posted!

 

It could be leak and/or there isn't enough pressure with power steering fluid.