Air Suspension Diagnosis Guide?

[LSPaul]

Car in question's a '93 LS w/ the air suspension. The issue's not atypical from what I've seen around this forum: In the "normal" ride height mode, once the car's switched off, one can hear air escaping from the area of the left rear strut and subsequently that corner gets the "droopy butt" syndrome within minutes. However, with the system in the "high" position, it holds air just fine, so long as the air compressor's not running immediately before shutting off the engine and/or it's not parked on a steep incline.

In posts I've read here, some say that those issues would be with the 'bag, others say the problem would be an actuator not working correctly.

Is there any sort of definitive diagnosis and testing guide/sequence out there for the air ride system and components? I've searched the archives and the interwebs but haven't really found anything helpful.

Thanks in advance,

Paul