The point here is that what has apparently change is the version of the Ide. The sketch has not been modified at this point in anyway. It is currently identical to what has/is successfully running on a MEGA2560.
My hope was that someone would have a "secret" revelation about the behavior of 1.8.16 versus 1.6 vintage IDE. It's really hard to understand the issue as I'm sitting here with my "device" running the sketch with the very device that the current IDE says won't "fit" in memory. Thanks for the suggestion to send the code though -- very generous 