[ale] missing superblock after upgrade

[mhirsch at nubridges.com (Michael D. Hirsch)]

I just upgraded my home computer to Mandrake 10.1.  It appeared to go well, 
but upon reboot it was unable to mount my /usr/local partition (/dev/hdb3).  
I can't imagine how that got messed up as I wouldn't expect the upgrade to 
even touch that partition, much less write to it.

Anyway, fsck complains that it can't find a superblock for it (it is supposed 
to be ext3) and that I should try another block.

Is there any way to figure out where the superblocks are?  The error message 
suggested trying 8192, or some such, but that didn't work.  Are there some 
common alternate superblocks?

Thanks,

Michael