A car came to me a short while ago with a hard suspension complaint.
No work on the hydraulics effected any improvement. The final thing checked was the ride height (It should have been one of the first) and this was found to be some centimeters too high.
Re-setting to the correct heights - it was a 1997 model so the specs were not as the original pre-1995 - transformed the ride and sent away a happy XM owner.