[news]

In message , Suzanne S. Barnhill
writes
The duplication of Heading 1 almost certainly results from a manual page
break before the heading. Delete it and format the heading as "Page break
before."

No, there was no page break, and all Heading 1 lines are formatted as
"Page Break Before".


For the rest, do your headings actually use Heading 1 and Heading 2
(built-in styles)?

Yes.


If they use other styles, have you selected these in the
TOC Options?

N/A


Are any of the headings in text boxes?

No.

However, I have now persuaded Word to update the ToC. To do this, I
switched from Print Layout View to Normal View. But instead of updating
the ToC almost instantaneously, everything froze with the hourglass
showing for over 6 *minutes* before the new ToC appeared!

As I explained originally, this problem only arose after I copied some
pages from another document. In that other document, ToC update works
fine.

Weird!

I am now tempted to create a new document and paste the old document
into it, to see if the problem goes away. However, if I do this, how do
I include the tracked changes in the new document? Readers will need to
see the changes.

--
Ian