Accidentally ran grub-install incorrectly, now have a grub prompt but no menu

Accidentally ran grub-install incorrectly, now have a grub prompt but no menu

tl;dr: I fat-fingered grub-install, "correctly" re-issued it targeting the
/boot filesystem on /dev/sda1 but it isn't reading grub/grub.conf unless I
expressly tell it where to look using the grub prompt tools. How do I fix
that?



I have a critical CentOS 5 system with multiple hard drives that aren't
hot-swappable. That's a bad idea, by the way.
The first drive contains /boot, then two mirror mdraid partitions for the
OS and data. The second drive contains just the two mdraid partitions.
The first drive is very slowly dying, so I added a third drive to prepare
for the inevitable. I copied the partition layout of the first drive,
added it to the mdraid mirror, then used dd to clone sda1 to sdc1.
I had a hardware maintenance window last night and needed to reboot the
machine anyway, so I figured I'd take the chance to switch sdc to the boot
drive. As I only copied the partition layout and the first partition, not
the entire drive, I figured that sdc wasn't bootable. So after adjusting
fstab, I made sdc1 bootable and used grub-install to ensure that grub
could take care of things.
Only I fat-fingered the command and typed grub-install /dev/sda.
It gave me a warning about not finding the drive in the BIOS drive list,
so I assumed that it didn't do anything harmful. I re-issued the command
targetting /dev/sda1 instead, but got the same error. Hmm. Oh well, it
probably didn't do anything, right? Yeah. No.
When the system didn't come back up after reboot (printing GRUB GRUB GRUB
over and over on the console), I knew I was screwed. Apparently what I did
is irritatingly common.
I booted the machine into a live CD, used dd to nuke the MBRs on both sda
and sdc, mounted sda1's copy of /boot, issued the correct command (which
involves asking it to probe the drive list and giving an actual filesystem
location), and rebooted. What came up was the grub shell. I was able to
issue root (hd0,0) and configfile grub/grub.conf to get into the boot
menu, but I would have assumed that if I'd issued the command correctly to
begin with then it would have seen the menu immediately.
So, my critical system is running fine. I'm only going to be able to
reboot it once in the near future, so I'd like to get this taken care of
sooner than later.
So, my questions:
Is the current booting-into-grub-but-not-seeing-any-configuration fixable
without re-running grub-install? I'm terrified of the thing now.
If I have to invoke grub-install again, what should be the correct way? I
used grub-install --recheck --root-directory=/path/to/sda1/boot /dev/sda1
to get it into its current state.