UPDATE – Cheap Tubs
We finally removed the tub today and took a look. As many of you offered, the tub has been flexing.
You all were absolutely correct.
When looking at the bottom of the tub we could see “rub” marks where it was flexing. Also, with careful measurements, we found that the supports on the back wall were ¾” higher than the front. That is NOT “close enough” although Keystone thought so.
We will be building a new rigid platform and rear supports to place the new tub on, and it will be level.
Thanks again. As usual RV.Net members have shown me the right path.