Sinking Sleeper

Is it ever the right height? Has anybody adjusted the leveling valve?

 

I'd see if the valve has moved. If not pull the rod off and lift the valve arm and see if the bags come up.

 

Check and make sure that there is no contact between the top of the sleeper and the rails that the SUV is sitting on. Or that nothing is contacting the cab or sleeper. It does not look like there is enough space for the cab/sleeper to rise up and level off. If everything is all clear then check the leveling valve as Big Road Skateboard suggests.

 

Just check the height and reset, maybe the valve rod last ots position, if the bags are not leaking enough to keep the cab up and of the valve is operating normal there isn't much else other then where the bags ride beginning to bend inward, then again the leveling valve would compensate, only seen that on rust buckets where the aluminum was so corroded it became weak.
Also being a parking lot we don't want much movement, not 1 parking lot I owned had any suspension on the cabs

 

Looks like an airbag is blown?

 

Mine did that it was a faulty air suspension valve

 

579 pet done that, the plastic leveling valve broke the ball joint off, common on them, know another guys did same thing. shops don’t look, see how much air is in your cab bags, mine was just very little and cab was sitting down like that.

 

May be different but mine is this valve, The ball joint broke, allowed it to move freely, but when it went down it’d release all cab air.
Yours in photo is older model, but maybe give somewhere to look