I rigged up a Schrader fitting (like the inflation valve on a tire valve stem). Napa sells them. Hooked it up to a piece of tubing and connected it directly to air bag inlet and inflated it to about 75 lbs. Checked my adapter and tubing with soapy water to ensure no leaks. Checked it next morning. First bag checked was ok. Second time on other bag on same side, went flat overnight. If both checked ok, then it would be lines or leveling valve. Valves are cheap enough anyway, should replace while you are at it unless recent.These were rolling lobe bags.
I wouldn't worry about ride comfort on the old style. Just get the block off plates and move on. Leaking air beams are a pita.
