Busted Zipper
These zippers have been giving us fits for some time now. The teeth become unmeshed quite easily. And they don't easily go back.
I finally got fed up and did the low tech solution. I have some excess mosquito net. Looks like this will probably work well.
With the zipper permanently open, the tension wasn't keeping the tent wall in place. It was blowing in and out with the breeze, and defeating the purpose. So I wound up staking down the sides of the opening.