Thanks Conny

I know, I may sound stupid but after 2 years of struggling I was almost fed up!

about the shooting trouble list:

- it looks like now there's no leaking in the system ( at least nothing visible, no marks underneath the car where is parked)
- silica filter and paper filter are clean
- the pump is working

- not sure about the valves, in particular I don't know about the ventilblock; I can't say if is actuated or not, how can I check it?

- about the electricity I have a doubt; the battery (100amp bosch) is like 3/4 yrs old, it was already in the car when I got it 2 years ago. tha car wasn't running and I always charged it up with the charger in my garage.
when the mechanic worked on the mengenteiler he boosted the battery and since then also the power seats etc were working very fast and responsively.
after a couple of months the power seats stopped working all of a sudden, that was the same moment when the red dot of the suspension button stopped working too.

I understand about mechanic and a little of engineering, I can do most of the maintenance jobs by myself, but I don't know a shit about electronics...

is it possible that the battery isn't supplying enough power to feed all car's systems?

I'm just driving around the parking lot where is recovered and basically it never revs over 2500rpm in 2nd gear, let's say once every two weeks.