The step wheel cover is pretty simple, consists of the sliding track system, air cylinder, and the air solenoid valve.
I would remove the solenoid valve and try to clean it to make sure it sealing correctly.
One problem is the air cylinder they used was hydraulic so potentially the seals in the piston could fail. You might try putting some light weight in the air supply tubing.
The step itself can be removed to access the cylinder.
2002 Monaco Windsor 38 PKD Cummins ISC 350 8.3L
2005 Jeep Grand Cherokee w/5.7 Hemi