Power Steering, any clues?

[Wetfish]

Anybody know what the symptoms of power steering pump failure are? Mine is making groaning noises and has become a bit jerky. Changed the belt, which was slipping at low speeds. It’s not slipping now but is still groaning and jerky not smooth as it was. So is the pump on it’s way out, I’ve got a couple of spare pumps and as it seems quite a simple job I might as well try a swop unless someone can point me in a different direction.
TIA

[E_T_V]

First make sure there is no air in the existing setup. Check the level and top up as necessary then slowly turn the wheels from lock to lock several times to bleed the air out of the rack.