Land Rover Repair: air suspension fluctuation, land rover specialist, minor leaks

Question
My vehicle (diesel 2 series 2001 dHSE) seems to be dipping up and down slightly whilst I am stationary. The ride height indicator lights do not change however. I've tried using the ride height locking switch on the dash but this doesn't stop it so it doesn't seem to be a sensor. Keeping my foot on the brake pedal stops the fluctuation I think but the handbrake doesn't. I've had the system checked by a Land Rover specialist who took it for a run with the laptop hooked up - no faults were detected.
If I leave it parked overnight still on the normal ride height setting there is a slight loss of height (but it doesn't sink down to the bump stops) by the morning as it lifts back up when I start it - is this normal or is there a leak?

Answer
the non-return valves in your valve block are leaking by.  When the compressor runs air leaks past the check-valves and into the springs (the spring isolation valves are one-way.  they hold air in the spring, but allow air into the spring if it's at high enough pressure, -compressor discharge) After a little while the ECU notices the height difference, stops the compressor and lowers the RR back to target height.  Then the compressor re-starts and the cycle continues.  When you put your foot on the brake it stops the compressor, so the dancing stops.  The hand-brake does not stop the compressor, so it will continue to dance.

Losing height overnight is not normal either, you have minor leaks in your springs or at the valve block orings.

A valve block oring kit will probably sort out most of your issues.  An '01 probably doesn't need new springs or a compressor rebuild yet, unless it's got very high miles.