OK, I've tried the test version of mobi_header.py and it didn't work. Different error this time.
Code:
Status: failed
Traceback (most recent call last):
File "C:\Program Files\Sigil\plugin_launchers\\python\launcher.py", line 137, in launch
self.exitcode = target_script.run(container)
File "C:\Users\Jon\AppData\Local\sigil-ebook\sigil\plugins\KindleImport\plugin.py", line 113, in run
epub = qe.makeEPUB()
File "C:\Users\Jon\AppData\Local\sigil-ebook\sigil\plugins\KindleImport\quickepub.py", line 51, in makeEPUB
xhtmlstr, css, cssname = ml2html.processml()
File "C:\Users\Jon\AppData\Local\sigil-ebook\sigil\plugins\KindleImport\mobiml2xhtml.py", line 219, in processml
htmlstr += self.processtag(taginfo)
File "C:\Users\Jon\AppData\Local\sigil-ebook\sigil\plugins\KindleImport\mobiml2xhtml.py", line 445, in processtag
styles.append('font-size: %s' % size_to_em_map[sz])
KeyError: 'normal'
Error: 'normal'