Time machine is a big box of poop. I just changed the disk-wide permissions on my backup disk and it FRIED the old backup. TM no longer recognizes it! It's now attempting to create a new, 900+GB backup on top of the old 900+GB backup. The Files are there and they're in tact, they're just not the same permissions as before. How do I fix the permissions on a time machine backup so it recognizes it again?