[CentOS] lvm errors after replacing drive in raid 10 array

I thought I'd test replacing a failed drive in a 4 drive raid 10 array on 
a CentOS 5.2 box before it goes online and before a drive really fails.

I 'mdadm failed, removed', powered off, replaced drive, partitioned with 
sfdisk -d /dev/sda | sfdisk /dev/sdb, and finally 'mdadm add'ed'.

Everything seems fine until I try to create a snapshot lv.  (Creating a 
snapshot lv worked before I replaced the drive.)  Here's what I'm seeing.

# lvcreate -p r -s -L 8G -n home-snapshot /dev/vg0/homelv
   Couldn't find device with uuid 'yIIGF9-9f61-QPk8-q6q1-wn4D-iE1x-MJIMgi'.
   Couldn't find all physical volumes for volume group vg0.
   Volume group for uuid not found: 
I4Gf5TUB1M1TfHxZNg9cCkM1SbRo8cthCTTjVHBEHeCniUIQ03Ov4V1iOy2ciJwm
   Aborting. Failed to activate snapshot exception store.

So then I try

# pvdisplay
   --- Physical volume ---
   PV Name               /dev/md3
   VG Name               vg0
   PV Size               903.97 GB / not usable 3.00 MB
   Allocatable           yes
   PE Size (KByte)       4096
   Total PE              231416
   Free PE               44536
   Allocated PE          186880
   PV UUID               yIIGF9-9f61-QPk8-q6q1-wn4D-iE1x-MJIMgi


Subsequent runs of pvdisplay eventually returns nothing.  pvck /dev/md3 
seems to restore that but creating a snapshot volume still fails.

It's as if the "PV stuff" is not on the new drive.  I (probably 
incorrectly) assumed that just adding the drive back in to the raid array 
would take care of that.

I've searched quite a bit but have not found any clues.  Any one?

-- Thanks, Mike