The other day I had an old tar file that I could not extract. I got the message that the headers were corrupt from previous errors. I found an old post from 2005 that told me what I needed to know. Here is the command. No, I do not know what any of it means:

$ cpio -ivd -H tar < nameofcorruptfile.tar

My file was about 5 gigs in size and I lost a little of it, but not much.