After months of frustration with Yosemite performance problems, I finally gave in and completely re-installed the OS fresh. I reformatted the drive and did a complete re-install, but migrated my user files and settings when prompted via Time Machine, as part of the install process.
Question: How can I get the newly-installed OS to recognize my old Time Machine backups?
When I point Time Machine to my old backup disk, it shows "Oldest backup: None". I know that there's probably some GUID on the partition that doesn't match what's on the TM backups... is there any way to get my "new" system disk back into the Time Machine backup set without losing all the backup history?