Power Steering issue.

So today when driving I took a corner and all of a sudden herd a whine,
pulled over and checked PS fuild it was full.
Now when I start the car I hear a weird noise that sounds like
its coming from the top pully where the belt is.
Its hard to turn with no rpms but you give it gas
or when you have speed and its fine.
When you brake and try to turn it starts to get stiff again.

PS pump
PS belt
Rack

Which is the best way to go about this...
Thanks.