I've read about someone who bought a new Rhino that was missing the rubber o-ring.
I have what may seem like an odd experience. My Rhino leaked sometimes. I finally figured out that the extra little bit of the end of the hose material that stuck up inside the locking ring area was causing the leak. When I clamp the hose onto the motorhome pipe, if I would position the hose such that that bit was at the back/bottom, it would leak. But when I position the hose for that bit to be at the top/front, no leaking. This may just be an issue of the angles in my connection. But you might look into it.