If you're getting
Mar 4 18:37:21 hubble kernel: [ 1732.229554] st0: Incorrect block size.
then you need to do:
apt-get install mt-st
mt -f /dev/nst0 defblksize 0
and then
tar -tvf /dev/st0
works like a dream... Now 5 tapes to recover. Horaay!
