Since you did bring not over the registry keys from the old hard drive, there was a new machine ID created at plex.tv
Which basically means: a new server is added to your account.
I have now deleted your older machine from your account, but you can do so yourself in the future, at: https://app.plex.tv/desktop#!/settings/devices/pms
After this, you’ll need to force your clients to fetch your current list of server from plex.tv again and don’t use cached information.
The quickest way to do this is to ‘switch users’.
(If you don’t have any users in your Plex Home, which you could use to switch, you can either wait for the clients to refresh on their own or
sign out the client from your plex account and then sign back in.)
