After playing around for a while without success, I blew everything away except for the current about to expire certificates located in the directories where sendmail and apache look for them.
I then started at square one including registering and proving that I owned the domains.
All went smoothly and when I was done I forced a renewal and the certificate renewed without errors.
I have no idea what created the error I was experiencing, and although it would have been nice to find out why, it appeared that it was going to be a real time sink.
I also built a script for cron to run once a month that will force a renewal, distribute the new certificates in their proper directories and send me an email as a reminder to check on how it went. If there are no problems with this install after several months, I will go back to the daily check with renewal one week before expiration.
Thanks to both of you taking the time to reply