Read error on bootinfo structure at 0x800

UNIX SCO
1

hi

One of our SCO 5.0.6 server is crashing every second or third time during rebooting with kernel panic.
According to this SCO manual:

http://wdb1.sco.com/kb/showta?taid=106181&qid=1689366546&sid=504668569&pgnum=1

I've saved dump image into a floppy and I've done the following steps:

# cd /tmp
# ldsysdump image

Use Floppy Drive 0 (/dev/rfd0) by default.
Press <Return> to use the default device.
Enter valid Floppy Drive number to use if different from default.
Enter t to use tape drive.
>

Enter type of floppy used to save the image :
  1 - double density 360 KB diskettes
  2 - quad density 1.2 MB diskettes
  3 - double density 720 KB diskettes
  4 - high density 1.44 MB diskettes
  n - no, QUIT
> 4

Insert diskette and press <Return>, or type q to quit >
Please wait.

dd ibs=18k count=80 if=/dev/rfd0135ds18 obs=1k |
        uncompress | /etc/sysdump -qi- -o image
uncompress: stdin: not in compressed format
dd: write error: 

# crash -d image
dumpfile = image, namelist = /unix, outfile = stdout
Read error on bootinfo structure at 0x800

BTW I cannot mount this floppy with a dump file:

# mount /dev/fd0 /mnt
mount: cannot stat '/dev/fd0'

Howto read this dump file?