New iMac wants to "inherit" wrong TimeMachine backup

I replaced a failed 2008 iMac with a new late 2012 27". Data was rebult from a full migraton from the old hard drive. Everthing is running Mountain Lion. (10.8.2)

The new machine however wants to "inherit" the Time Machine backup from a completely different computer on the network? Names aren't even close.

There seems to be no command to force it to inherit the right Time Machine backup.

I did look at the http://pondini.org/TM/B6.html instructions for these situations, however the directory in my Time Machine looks nothing like what is described there.

At the root level of the time machine are several packages named after their respective computers, and a folder "Backups.backupdb" that is empty.

Suggestions?