Tom, you should check the integrity and operation of the valve Mike illustrated, but also examine the bladder for damage. When the engine is on and the coach in gear, opening or closing the door against an inflated bladder can tear it... yes it can happen, like when the rig was new my copilot thought the door wasn’t totally shut, and opened and closed it while we pulled away from a parking spot and I had my foot on the brake pedal. Oops. We were lucky the bladder was okay, but that was before I understood how it worked, and that you shouldn’t do stuff like that.
The bladder should deflate when you’re out of gear. Can’t recall whether the parking brake needs to be on (due to illness we haven’t driven it for over a year), but I’m never in neutral without the air/parking brake on anyway. But if not, you could test bladder operation by opening the door and putting it in gear, but leave the parking brake on. Take the rig in and out of gear to see if the bag Inflates and deflates as designed. Someone else here I’m sure can confirm or debunk that notion.
The other thing oft overlooked is the window drain covers, Atwood I think on yours. Hard to imagine but without those covering the weep holes, wind noise increases more than you’d think. Ordering several left and several right ones helped ours, and provided spares should any fall out again. Windows toward the back of the coach were no big deal, but replacing missing ones in the driver’s and front passenger windows did reduce wind noise - it wasn’t total, but the improvement was noticeable.
Joel