Rather than fiddle around, I decided to erase Program B and then re-install it.
I then tried the Program Cycle run, and the fence top rotors were off. When
the cycle had finished, I tried a Single Station watering that was the problem
when I tried yesterday. Again the fence top rotors were off. So it does look like
a software-type issue was implicated. [Ctrl] + [Alt] + [Delete] was the way!
Obviously, the feeble memory recall was even more feeble than I thought.