[Richard]

Here is something to think about. Right now, you are unsure what is leaking, and even more unsure what the leaking device is called. All of the stuff under there is STANDARD truck stuff. Nothing is proprietary or Newell specific. You really don’t have the equipment to safely change out the device even if you had a new one. All of the air will have to be exhausted from the coach. I have worked on air stuff in that area, and it is tough and nasty sledding. Lot’s of coach yoga (contortions) involved.

Since it is standard truck stuff, find a reputable truck repair place that will work on a bus. A bus repair place would be even better. They will have the parts or can access them the same day.

I would not order parts on what you “think” is leaking.