@
Mickyzip - have a look in the calibre editor subforum or the sigil forum - there are various tools for cleaning up EPUBS that originate from PDF's, some are saved regex search and replace 'macros' for want of a better word, I think there's at least one a plugin for Sigil. Also have a look at the calibre-editor's functional S&R see ==>>
Function Mode for Search & Replace in the Editor
99.?% of PDF->EPUB conversions will require some manual intervention, even after all the automatons, so the editors are the best place to do the 'common' stuff before tackling the 'exceptional' stuff.
Another approach is to go via Word and use Toxaris' Epub_Tools Word addin, its in the Workshop forum - it can do a lot more than fix the common typographical glitches.
BR