Yup, I confirmed that the leakage was between the hydraulic pump and the engine. I had to flush the engine and change the filter and oil after that. I also tried to renovate the pump but the bolts were completely frozen. After I got tired of trying to loosen them I replaced the rear shocks with standard ones.
That was a good fix. The ride was much imroved and the car handled better. The reat end was still to low though.
I drove with that for about 3 months and after that I also changed the rear springs for Standard springs i.e not designed for the hydraulics.
That was a big improvement. Not only is the stance of the car back to normal but the "wandering" at speed is much improved. Its now much better to drive. Probably because the earlier sagging rear end changed the steering angles a bit.
Good luck/ Mikael