Land Rover Repair: 96 Rover EAS winks, ear shot, intermittent problems

Question
I replaced the whole system about a year and a half ago and this summer i noticed it was winking again. I come back from my commute train to see that one side in the front was lower than the other 3 wheels and the rover was winking (what i call it) my mechanic said that I should keep the "lock" button inside on. and one other guy(don't remember if he was the other mechanic or what)  in ear shot said start the car with the door open so it raises faster.
They checked out the bags or what ever they're called and no leaks were detected. and it is not every time or one side or the other.

Answer
Intermittent problems are the toughest to figure out.

The lock button will do nothing if you have leaks, opening the door will allow the compressor to refill the tank before trying to raise up, only an issue if you have leaks.

Since it's lowering randomly it's likely a small leak in that spring.  the leak will be open at one height, and self sealing at another height.  Have a good look at that spring (and the others) for small cracks/dry rot.  If they look bad it's time for replacements.