Solution of sorts:
Have to give this anecdotally as the underlying issues are not clear. I had a whole description of what we found and what we think might have fixed it but going back over it all I can only give you apparent symptoms.
- The problem number is gone.
- It turns out that the problem number in the permalink URLs was the trackback ID #, padded out with zeros. Found this while examining the database (via phpMyAdmin) to try to find differences between the blogs.
- Previous "All pages" republishing has not changed the URLs but one attempt this morning did, and the numbers went away with that even.
- Internally in the database there are still many entry records with the old, incorrect URL in the trackback_URL field.
Hope this might be helpful to somebody.
Thanks to ONM and Su for replies. Your kindness and time are very much appreciated. Thanks.
Su: I agree that this tag value should have made no difference re: pulling ads and it may have been some other coincidence occurring but the appearance was this: that when we navigated in the same browser from the same IP to a URL without the tag appended then we got a meaningful ad but when we went to the same URL with the number tag appended to it, then we got PSAs or nothing.
Go figure.
Thanks again.