problem with 'tar'

[Leuven]

I am currently attempting to upgrade our local system to
release 1.4 of Sun UNIX.
The source code is on three cartridge tapes.
Unfortunately, however, using 'tar' to extract the files
from tape results in a 'directory checksum error' message
and the program halts. Using the '-i' switch (ignore such
errors) does not work.
I would be eternally grateful to any UNIX-maestros who
could suggest a solution for, or a way of getting round,
my problem.
Answers (?) to the above nets or preferably direct to
		Lieven Jaspaert
		address  ...!mcvax!euroies!ljaspaert
		(also on EuroKom)

Thanks in advance !