pasusan wrote:
The one thing that I've heard of is the plastic round disc that is cut out of the tank to add the outlet pipe sometimes is left in the tank and can then try to come out with a dump and clog the opening.
This is a real thing. It happened to me. I bought my first RV brand spanking new. When it was about 2 years old, I was dumping at home with a Flojet Macerator and had a clear section installed so I could see when the effluent was clear. (Nice big word.) All of a sudden, there was a CLUNK and there was this nice round disk in the clear section. Of course, it didn't get macerated, but when I took the macerator off the RV, that nice round disk was where they had cut one of the openings in the black tank. After that, my black tank drained MUCH faster and better. (If I had been using the stinky slinky at the campground, I would have never known it had been in there.)