[Richard]

One of the useful tools that many of us have made to help with air leak diagnostics is a shut off valve with guages on both sides that we insert between the six pack and the air bag line. Inserting that tool tells you a lot about where to start.

In your case, if you air up the bags and shut the valve, and the coach squats, then you have an air bag or tank leak. If it stays up with the valve shut, then suspect the valves in the six pack.

If you shut the valve and the pump will build pressure, then suspect a problem with the travel solenoids or height control valves.