The lost datas importance or unimportants would matter in making my decision.

Warlord wrote:

The lost datas importance or unimportants would matter in making my decision.

It's a very stable, barebones Win98 SE setup with the right updates and drivers, plus saved game data from the past several years. Ideally, I'd like to retrieve it all, but it's not a catastrophic loss if there's no possible way.

murrayman wrote:

Looking at the circuit board from beneath, I don't see any broken traces, so no visible damage from shock on the outside.

To examine the circuit board, you'll need to unscrew it from the hard drive and carefully flip it over to check the component side. You may have a blown fuse or diode near the molex connector.

Took a look at the circuit board and found no broken traces or other red flags. I found an exact-match replacement on eBay and decided to give it a shot. Swapped the old with the new and tested it with power, and now it does cycle, but not to full speed. At about half-speed, it gives an audible knock, and spins back down before repeating the same thing. Not sure why the old circuit board wasn't allowing the motor to spool, but although this one does, it seems the HDD is indeed damaged.

I would be more inclined to say that the replacement board you bought is also faulty. The knock kinda sounds like it is slamming the head into park mode or all the way to the inner part of the platters. Either way, it is slamming the head arm into one of the stop bumps.

Of course if could be that the spindle motor is going bad. In the past I have opened up dying drives and manually helped the spindle start spinning in order to retrieve data from the drive.

If there is no power only two things come to mind and one is very very unlikely as you would have had to make the change yourself with a utility, chances are the controller got zapped by esd or got a cold joint. The heads should be parked anyway and that shouldn't be the issue.