So, “I can’t get there from here”.
Thanks Cubecolour, I’ll see if the theme author can help.
Or I’ll try to use the same code approach I used in the theme CSS in each static page for navigation – using the “#secondnav”. Or, better still, since the theme seems to allow a secondary menu, I may be able to use that. The required layout is for the image menu below the header and main menu above the header.
Or perhaps some kind of a slider plugin for the secondary menu. One of the things I love about WordPress is that the more you learn, the more options you have to solve unusual issues – making WordPress more flexible than it at first seems.