The code in post 4 should change superscripts in the main text leaving footnotes intact. And this is the fastest way (as far as I know).
But (just in case) try this one. It doesn't use With...End With block:
Code:
Sub Superscripts_To_Regular_MainTxt()
'Change all superscripts to normal text only in wdMainTextStory (1).
For Each aStory In ActiveDocument.StoryRanges
If aStory.StoryType = wdMainTextStory Then aStory.Font.Superscript = False
Next aStory
End Sub