Thanks for the answer Hell Razor.
Generally this is how the latest problem arised. The car was administratively stopped from moving for 1 month
, and I forgot her at normal level and I think it has anti-sink valve, because it sank very little from the normal position. Before this "problem", the LHM was between the marks at max height, but now the indicator goes down when I switch to max level. I have a minor (bigger now) leak from the pump, but I have the O-rings already for replacement thanks to the information from the forum. I think the accum sphere had ruptured because the thick time was bad already, when I took it. Also it seems, that during its stay the car developed a leak from the steering rack, but it may be also an engine oil dripping from the head covers, not sure (I've put some silicon there). Because I'm about to change also the groomets, then I will know for sure.
Till now I had replaced both front and rear disks and break pads, and the nipples are already sprayed with antirust spray, so when the time comes for bleading out, I think they will unscrew without a problem.
OK, just to see if I understood correctly from your feedback: the spheres should be pressurized (with nitrogen) after the mounting, I mean this is imperative or? -> will the new spheres take a little trip to the place for pressurizing or the car should not be driven, before they are pressurized with nitrogen?
About the sufficient LHM fluid into the reservoir, because as I mentioned above I'm short with it, shoul I top up before I start the removal of the spheres or the top up should be made last, just before turning the egine on with the 12 mm head screw closed?