[Fulltiming]

Chris, as you know, most of my experience is with 1990+ models so things could be different on your coach but here are a couple of thoughts. On the drain for the air tanks, on 1990's models, the wet tank is about the rear axle and the front and rear brake tanks are behind and way above the front axle, impossible to get to them without crawling completely under the coach (with the usual admonishment of never get under a coach that isn't well cribbed. If the system is depleted of air, you can remove the drain petcocks and either clean them or replace them. The air box drain, if unopened for a long time can be full of thick oil that will not come out. At least on my coach, the canister can be unscrewed and the entire canister dumped and wiped out. Old oil over time can be more like grease in consistency.

On the 120 v compressor, there is a dash switch to turn it off and one on most Newells I have seen. That switch is placed in different locations so you will have to look around for it. On many Newells, there is a fitting in the engine compartment that is set up to allow shop air to be attached. On mine it is near the rear of the coach on the passenger's side accessed by the side engine access door. I put a valve on mine because the fitting was leaking air. Of course I replaced the fitting also.

If you coach is leaning when the engine is not running and it is in travel mode, I would start with checking the travel height valve and solenoids related to the driver's rear air bag.