I got my computer back yesterday after Apple replaced the mobo. I tried to do a Time Machine backup, but it kept failing and wouldn't tell me why (there was no error message, just "Failed". So I tried to reset it by switching my backup drive to a different partition on my external and then switching back to my original partition. Now, instead of seeing that there's already a backup for this computer in the the Backups.backupdb folder on the HDD, it tries to create a new folder ("*****'s Computer 2") and start from scratch. How can I get it to recognize that there's already a backup there?