A few lessons later I came across this post and what he had explained in the earlier video finally clicked.
To prevent trouble the sequence of the initialized variables must match the sequence they get declared in. The compiler is trying to say I’d simply overlooked this detail.
I now have 7 files and special messages to the compiler that prevent double-including header files. This lesson doesn’t get easier. Find the speed controls because it starts to move even faster but persistence and repetition give things more time to sink in.