However, on Dec 8 my connection stopped adding headers to Agent. The
msg at the bottom left corner of the screen initially says 'connected',
but then immediately says 'finished retrieving new headers', but no new
headers appear.


Hi Walt,
The problem occurred because you are on a new server, and it has numbered
the articles in the newsgroup differently. Most likely your Agent software
think you have read (for example) up through message number 20,000, but the
new server calls that article number 200. So it thinks you have already
seen message 200.

The solution is to unsubscribe to the antenna newsgroup and then
resubscribe. Then you can retrieve all of the articles that your new server
has.

Hope this helps. And congratulations on the QST article. Very interesting.

Rick K2XT