The (F) notation follows the drive which it refers to. So (F) refers to sdb partitions.

Do something like:

Code:

# mdadm /dev/md0 --remove /dev/sdb1
# mdadm /dev/md0 --add /dev/sdb1

to first remove the faulty partition and then add it back to the raid md0.
Then the array will be rebuilded automatically.

Before, please check that sdb is a healthy disk.

You do the same with all your three raids, of course using the right partitions.

BTW: you do have backups, don't you?
--
Bye.