DiskWarrior cannot attempt repairs if the Apple partitions of the target drive are not intact. Remember that DW is a directory utility and not a disk utility. The only intervention in a drive's logical structures that it ever makes is to repair the boot blocks after it has repaired and replaced the file directory. It is also not partial to SCSI, FireWire or USB connection problems.

You may have more success in your operation, which reads as if it were a rescue operation rather than just prudent housekeeping, if you archive the target drive's contents, reformat the drive, restore the data, and only then use DW to polish the doorknobs and dust the shelves. Normally you would just use DW directly on what is at the moment your target volume.

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