Dear all,
I have resolved the problem. I decided, after a bit of research, that a lot of the tools out there are not too good when it comes to epub 3.0 and apparently some of them (e.g. Sigil) are not keeping up. Calibre apparently isn't completely 3.0 safe either. I found a tool called Oxygen Author, downloaded a trial subscription, and it immediately took me to the exact spot on the file that needed fixing, and flagged the epub validation errors "LIVE" as I made corrections. I saved the corrected, cleaned up file, and it passed epub 3.o validation.
If anyone is interested in Oxygen, here is a link for a trial
http://www.oxygenxml.com/download_oxygenxml_author.html
I do want to say one other thing. I appreciate the replies I received, and I am sorry about the ugly code. I am not an epub expert, I don't write original code...what I do is publish books using Indesign and other tools, and then translate them to ebooks for the authors. I need the easiest, simplest, quickest way to do that, and so I use tools that can generate some damn ugly code. My sincere apologies. But perhaps in my fumbling around, I have been able to help other newbies who, like me, are not purists and just want to get the job done. My thanks to all, I appreciate you very much.
Jose