I had a 2001 S that I was aligning for a body shop. This requires reading the ride height with a Romess inclinamometer. It was wrong so I was trying to calibrate the height (with SDS) and every time I added height to a side the pump ran but the car didn't rise. The pump is under the right headlight and the area was still disassembled and the filter for the pump was dangling. By dangling it had pinched off the inlet and as such no outlet output.

Its not likely that you have such a restriction. Its more likely you have a lousy pump or a big leak if the suspension is down. The point of my story is you aren't tooled for this, the easiest of your three problems.

All three of your problems require a SDS for evaluation and final adaptation.

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician