I forgot to angle the awning one time on our stick and tin Jayco Eagle 5th wheel. After the storm, I couldn't open the door. I squeezed out to find the awning all bellied out full of water. I got lucky that nothing broke but it took quite a while to get the water out by pushing up on the fabric from underneath. Never forgot to angle it after that.
The black tank ordeal is a strange one. Hopefully no more leftover plastic inside. Could have been one of the kids accidently dropped something in. Been there. They were fascinated by the toilet flush. Once our daughters grew up and moved out, we no longer had these strange window, vent, toilet and other odd surprises. I sure miss when they were little.
I almost forgot the awning tube bent from the weight of the water. I straightened it the best I could by hanging from it while turned with the bow up. It worked but the awning never rolled up flat on it again.