Power steering problem
 

UK Turbo MY98

From cold, it's fine, but after 15 minutes or so, i start getting a whining when I turn the steering wheel.

Had a look at the fluid, looks fine. Belt doesn't seem to be slipping and the noise doesn't seem to be coming from the pulley.

Bonnet up when its hot, and if I turn the steering wheel I can hear a click from the right side of the engine bay, with the whining.

Pump on its way out? Bad fluid? Sticky valve?