Spot on again, Doug.

Instinctively, I used the squared up nipple advice, even before reading your tip!
I also kept a close eye on roundness, and appear to be in good shape there.

I don't have the dishing tool, but kept flipping the wheel to monitor that, as has been suggested.
At one time I did tighten all the spokes on one side, and that corrected it.

The seam is noticed by feel, ever so slightly, but filing scares me due to scratching.

A video shows my result, but I'll have to figure out how to upload it!