Since Mozbackup may have bugs, I suggest repeating the transfer, but manually. - on old hard drive, I don't remember Win 7, but your profile is probably either at

  C:\Documents and Settings\[username]\Application Data\Thunderbird\Profiles\  or at
  C:\users\[username]\appdata\roaming\thunderbird\profiles   

- Using File explorer, copy the folder and store it in new PC at

  C:\users\[username]\appdata\roaming\Thunderbird\profiles 

- press windows key and 'R' key and enter thunderbird.exe -p to start profile manager - click 'new profile' and enter a desired name, e.g.,OLDPROFILE and then, next, select browse button to locate the transferred profile.

Thanks David. I followed your directions, but I may have messed up. Thunderbird showed it found the old profile, but when I clicked to continue a popup read enter your name and your existing email address and password. I entered my current email address and password. I opened Thunderbird and the old profile is not there. When searching for it there is a series of letters and numbers preceding the old profile name. It is dpu9xu7d followed by [ .OLD EMAIL ADDRESS]. I don't know what to do now. Any ideas?

David, attached is a photo of the PROFILES folder now. Should I drag and drop the dpu9xu7d.pi@atlantapi.com folder into the PROFILES folder, or what?

It appears the TB Screen photo of the profiles folder did not attach. Here goes again.

Here's a fresh suggestion. - uninstall TB and install version 102, the latest release - start TB and ignore request for email setup. Instead, click HOME tab - on that screen is an IMPORT option. Click that and select the option to import profile. - select the profile you know to work, and click to start the import. That simplifies the import process considerably.

I do not suggest modifying content, as one of those was your working default.

David, I have made a bigger mess now. I do apologize. I used MozBackup to restore the pcv and it added the pi@atlantapi profile to TB. But there are no messages in the inbox even though the profile properties shoe over 3GB. So like a fool I apparently moved the entire profile to the TB program profile pi@atlantapi.com, and now all of the profile contents that were in the Roaming/Thunderbird/Profiles folder is showing in the TB program profile pi@atlanatpi.com. I uninstalled TB and downloaded version 102, but upon installation it went directly to the same old TB program. I know of no way to resolve the issue I have now created. Attached is a photo of the pi@atlanta pi.com TB screen.

Do you still have the original profile? I have read in several places that Mozbackup has bugs and, to my knowledge, is no longer supported. Your screenshots aren't appearing. I suggest using jpg files, if possible. I repeat my earlier proposed of steps, beginning with a full uninstall.

David your suggestions solved the problems. I greatly appreciate all of your help and patience.

GREAT! Nice to hear.