Hi Gord, I've attached a fixed up version here that is now a solid and should boolean ok.

There were some other problematic areas of the model, the entire bottom wasn't all aligned to be on the same plane and there was a kind of awkwardly squashed corner spot in one area.

To make this fixed up version and have it be smoother, I set it up like this and selected these 2 edges:



And then used Construct > Blend to put in a smooth blend surface:



- Michael