ZR Power Steering

[LFB531]

I've just swapped out a known good engine and ancillaries into a replacement ZR and all is well apart from the power steering. It (the pump) mutters away at tickover and positively groans when under load although it still seems to be working fine. I bled the system fully and there are no leaks, there's plenty of cavitation in the reservoir when under load though.

There was none of this in the old car even after the accident which brought it's demise.

I'm inclined to whip off the belt and run the engine without just to make sure it is the pump suddenly crying enough but wondered if I might be missing something more obvious. Any ideas out there?

Thanks, Duncan.