Julian,
Sorry, but gmail does not allow me to reply inline, or to select what I quote. I am using the only option I have.
I am not and did not ignore Frank's advice, which included a *count* of the files in /etc/apt/trusted.gpg.d. That advice was followed and was a dead end. Frank's advice was that the keys seem to be correct. There is a bug somewhere in here, I just don't know where. I did not try to fix anything from a clean install before this issue showed up.
I do appreciate you responding to me, but it's really not helping that we seem to be talking at cross purposes. I am not a Debian dev, but do have a technical background. So, I have tried my best to listen to advice, and to do what research I can. I am happy to follow any clear instruction, and would really like not to have to reinstall the operating system to fix what appears to be a simple problem. I understand I am using Testing, but there must be a way out of here.