Appears the shower drain is blocked by hair. Will try the baking soda, vinegar, hot water treatment and plunger. Any diagrams on the drain and trap? Seems to be sitting right on top of the grey tank with little clearance. Thanks.
Run hot water for a little while to loosen up any grease holding it together then push it through with a plunger. Worst case is to run a plumbers snake through but I realy doubt you would have to do that. You would probably have to drop the grey water tank to get to the trap which would be a PITA so hopefully the plunger will get it.
David
Maybe use a long tweezers to pull the hair out? I've had the shower pan out to R&R the drain on ours and it's not a simple P trap (no room). After some tweezing (if that's a word), use your vinegar/baking soda idea and then the very hot water. PITA to get at the plumbing, so I hope that works.
In my 2014 model, directly attached to the shower drain, is a 90 degree elbow that in turn is connected to a waterless trap called HepvO (https://hepvo.com/). The trap is then attached to the vent pipe coming up directly from grey water tank. This horizontal distance of this setup is about 16". It shouldn't be too hard to clean that out. It is probably a good idea that any 'snake' be blunted? plastic? so as not to damage the internal rubber diaphragms of the HepvO.
The rather expensive HepvO allows the shower base to be installed just over 2" above the trailer floor. (Just another reason to like my LL.) Best wishes. GK
Baking, soda, hot water and vinegar did the trick. Thanks for the info on the valve. I suspected it was installed but couldn't verify. The least intrusive measure was the best.
Gordon