You should look into the Hyperlink & Cross References Panel.
Hi Willi. Thank you for an idea of where to look. In that panel, while it let me look at all the hyperlinks in the document, I did not find any reference to the anchor or old link.
Can you say a bit more about how I can find the old one to eliminate it continuing to come up every time I export?
I found it!
Since you were referring to the hyperlinks, I remembered which of the 162 pages I had copied something into from the old file. Sure enough, there was a hyperlink typed there, but it was not hyperlinked to anywhere. I linked it to where it was supposed to go and now the error does not come up when I export it.
Thanks again Willi for getting me thinking in the right direction.