Weak Hydraulic Pump

[Jugostran]

Hey all!
I have a quick question about my HP pump. I recently had the pressure regulator rebuilt, so that is no longer causing issues. However, there are still issues possibly related to the HP pump.
The symptoms are as follows;
1) The power steering feels really weak at low speeds (to be completely honest it feels like it doesn't have power steering at all)
2) When the pressure regulator valve clicks, the car enters this really long phase where the HP pump makes this awful (and almost grinding) noise. However, when I blip the throttle the engine stops struggling and starts running fine.
3) A bit of an extension of point 2). When the pressure regulator clicks, the engine RPM drops dramatically and the entire car starts shaking. It does eventually stop, but again I usually just blip the throttle in order for it to restore to a stable idle.
Is this indicative of a bad HP pump, or is something else to blame?

[rutter123]

Yes sounds like Yr H. P pump is struggling to maintain pressure, no PAS on cold starts is indicative of this, also worth checking that your accumulator sphere isn't flat/dead.
H. P pumps can be rebuilt if you can find a small engineering company to do it, the "top hats" inside the pump will need a re-grind with new springs/seals etc, there is a shop here in UK that do it for around £200 on an exchange basis, not sure on facilities where you are.
I'm sure there is a thread on this somewhere.
Getting the pulley off the pump and opening the pump is quite a job in itself.

[Jugostran]

Yes sounds like Yr H. P pump is struggling to maintain pressure, no PAS on cold starts is indicative of this, also worth checking that your accumulator sphere isn't flat/dead.
H. P pumps can be rebuilt if you can find a small engineering company to do it, the "top hats" inside the pump will need a re-grind with new springs/seals etc, there is a shop here in UK that do it for around £200 on an exchange basis, not sure on facilities where you are.
I'm sure there is a thread on this somewhere.
Getting the pulley off the pump and opening the pump is quite a job in itself.

The accumulator sphere is new, so I think a new HP pump is in order. I suspect I can get one for way less here in Serbistan.
Thank you for taking the time to explain it all. I was asking just to make sure before I go ahead and order parts.