Got the email and am looking forward to the repair process (which is not something I could usually say)!
I received new mesh and spline and affected the repair:
I first started by taking out the current spline and mesh. I then tested the fit of just the frame on the tank - it fit well, so this confirmed that the problem I had lay in the mesh pulling the frame out-of-square. With this confirmed, I set out to replace the mesh. I took my time and did my best to keep everything square. I also worked to keep the mesh taught, but not to distort the frame any. I thought about putting in spacers to help prevent such, but decided I didn't want to crack or scratch anything (I doubted such would really happen, but better safe than sorry).
I must say - it is not easy to set the mesh. The spline fits quite snuggly (more-so than the numerous window screens I've done). Pushing it into the channel causes the mesh to be pulled slightly and runs the risk of cutting it. That (the cutting) happened a few times - mostly on the outside edge, though. There's only one spot where the mesh got cut on the inside, and that is in an area where it's unlikely to cause an issue. I'm not worried about it. I found that stretching the spline a bit helped to set it in, but I had to be careful to only stretch it a little, else it would pull the mesh too much and force it out of square. A delicate balance that made me appreciate the factory quality even more. Trimming the mesh was a simple matter; running a blade along the outer edge of the channel snipped the excess mesh cleanly.
When I went to fit the lid back on the tank, it fit better. It's not a perfect fit; until near the end, I didn't account for the spline pulling the mesh as it was set into the channel. I think only the fact that I started off with the mesh loose prevented me from having the same problem as I initially had...
I'm content with the lid - it's better than I could have built myself and will last longer. Doing the repair myself was satisfying. It could have been done better, I'm sure, but I prefer to do for myself when possible - and the result is passable, at least. I appreciate that AA was willing to give me the chance and feel (hope) that it was a win-win solution.