[DMSmillie]

You're using "type='text' " twice in your OPF guide, cyberbaffled. That type defines the "start reading" location, so you're defining two "start reading" locations - there should only be one. The only guide items that kindle recognises (I'm not sure about other MOBI ebook readers) are "cover", "toc" (for an HTML table of contents which is part of the book content) and "text" (defining the "start reading" point in the content).

Edit to add: Kindlegen will also accept "type='start' " as defining the "start reading" location, but "text" is what is in the EPUB specification, and Kindlegen clearly accepts it also. I know I've used it without any problem when creating MOBI files.