Russ,
Thanks for the reply. I realize that this probably isn't the most appropriate forum for this discussion, but we'll plow forward until we get slapped by the moderators.

In my case, here's the background:
This drive was the HDD in an IBM Thinkpad X30 that is primarily used by my wife. She said she left the TP unattended for about 1/2 hour and returned to find a POST screen with 'Operating System Not Found' displayed (assume she had a BSOD followed by a reboot). The drive was spinning in the X30, but I could hear nothing but the drive spinning (no scratching, thrashing, etc.). To confirm that it was not a problem with the X30, I removed that drive and installed another drive which I had built some time ago for the same X30, and it booted fine. So that eliminated the X30 as the problem.
I then took the drive and attached it first to a USB enclosure, then to a 2nd HDD enclosure in my trusty old TP600, which I've used many times to restore corrupted OS partitions, recover 'erased' data, etc. It does not even recognize the drive, but display the following symptoms: The drive spins up, then a fairly quiet series of head seeks occur in rapid succession (7-8; can't quite tell for certain) then about three seconds' pause, then another series of rapid head seeks. The cycles of head seeks/pause happen 16 times, then... nothing. The drive continues to spin, but it is not recognized by a system. If I start a disk management program, I get the same series of cycles. This originally led me to believe that the PCA was the problem, so I began doing some research. I have a couple of other IBM/Hitachi drives and thought I could simply replace the PCA if I had a similar drive... obviously, that's wrong (and it's probably a good thing I decided to look before I leapt -- that's not one of my strong suits.

). My research actually led me here; to your post on this exact model drive.
I actually do not own any DR tools of any kind, and have done nothing more than the basic PD I just described. The data on this drive is irreplacable (wife did not back up her data to the NAS box as I told her to) so I am somewhat anxious about making sure this is done right. Chances are, based on what I've read, I'll send this to a professional (or someone more professional than me) to get the data off, and again remind the wife of the importance of backing up irreplacable data.

I'm sure this is probably pretty simple for you hard-core DR types, but that's not me (at least not yet). I'll be grateful for any assistance or advice you can give me.
TIA,
Tony