New harddisk: "CANNOT READ BLK" Cause?

[Jan Henrik Sylvester]

I got a new harddisk for my laptop, attached it via firewire, used "dump 
0aLf - / | restore xf -" (from the FAQ), and swapped it with my internal 
one. During that, I also migrated /var and /usr to separate bsdlabels.

On reboot during fsck (ad0s1f), I got:

CANNOT READ BLK: 251403296
CONTINUE? [yn] y

THE FOLLOWING DISK SECTORS COULD NOT BE READ: 251403296, 251403297, 
251403298, 251403299,

LOOK FOR ALTERNATE SUPERBLOCKS? yes

32 is not a file system superblock
SEARCH FOR ALTERNATE SUPER-BLOCK FAILED. YOU MUST USE THE

Is there a problem with the harddisk? Did I do anything wrong? How do I 
find out?

Since I never used bsdlabel and newfs by hand before for more than 
trivial cases, I might very well have messed something up. Here is what 
I came up with.

Since I forgot to change it before swapping harddisks, I came up with 
this simple fstab:

/dev/ad0s1b none swap sw 0 0
/dev/ad0s1a / ufs rw 1 1
/dev/ad0s1e /var ufs rw 1 2
/dev/ad0s1f /usr ufs rw 1 2

This is my bsdlabel for ad0s1:

# /dev/ad0s1:
8 partitions:
#        size   offset    fstype   [fsize bsize bps/cpg]
   a:  2097152       16    4.2BSD     2048 16384 28552
   b:  4194304  2097168      swap
   c: 314568702        0    unused        0     0         # "raw" part, 
don't edit
   e: 16777216  6291472    4.2BSD     2048 16384 28552
   f: 251658240 23068688    4.2BSD     2048 16384 28552
   g: 33554432 274726928    unused        0     0
   h:  6287342 308281360    unused        0     0

This is the fdisk partition ad0s1:

sysid 165 (0xa5),(FreeBSD/NetBSD/386BSD)
     start 63, size 314568702 (153597 Meg), flag 80 (active)
         beg: cyl 0/ head 1/ sector 1;
         end: cyl 124/ head 254/ sector 63

Anything else? (I could probably recall most of the commands I issued.)

Thanks in advance for any help,
Jan Henrik