How do I read a bad tape (tar)?

[R. Munroe]

I am having trouble extracting some important data from a cartridge tape.
I used tar and now can not retrieve the data.  The tape drive whirrs and
clicks a couple of times and then the system tells me to insert the next
tape and press <CR> to continue.  I know the data is on the tape - it justs
seems that there is a little snag that makes the system think it's
reached the end of the archive.  Question - is there anyway way of retrieving
the data (whatever is left of it) by either:

1.  Some unix command that will read past the bogus 'end of archive'.

or

2.  Are there any companies that specialize in data recovery that could help.

The tape is a 60MB Sony cartridge that was archived on a Silicon Graphics 4D/70
workstation (low density drive).  I also have SGI 3130's and 4D/25's
(Personal Irises) on site, that could be used if needed.  Thanks for any and
all help.

Bob Munroe
TOPIX Computer Graphics and Animation, Inc.
Internet: topix at utcs.utoronto.ca
AppleLink: CDA0695
CompuServe: 71160,3455
Voice: 416.971.7711