One of our imacs has decided to break its filesytem over the holidays! I've tried running fsck_hfs -r in SUM, it reports that it "failed after 3 attempts". Is there any other method to get the filesystem sorted? I've tried searching the usual places for tips but everyone seems to just say "tl;dr - disk warrior", is there really no open source tool to fix this?

If not, how can I get the files off this machine? I would use target disk mode but we don't have any Firewire 800 cables!