Ha! Figured out the format fix for MOBI files, so now have beautiful EPUB, MOBI and PDF files up at Smashwords for the guinea-pig chapbook. Add that to figuring out how to disable the various other dud e-formats, and we’re sailing pretty close to perfection here, people.
Have also been trying out various ‘make your own EPUB files’ mechanisms available on the web (do a Google search, there are quite a few) and so far all have fallen short of the Smashwords standards. The most promising was saving the formatted Word doc as an RTF file and converting it to EPUP/MOBI via Calibre. The result was certainly usable/readable and looked pretty good throughout – except for links. All the internal and external links got somehow deformed and de-activated. So I’m still swearing by Smashwords.