Seagate Momentus 40GB Head Problem

I have a 40GB Seagate Momentus laptop drive. The drive came in with a bad head. This is a single platter drive. I ordered a new drive, with an exact match on the Model number, HDA number, country, etc.

Many times instead of swapping the heads on a single platter drive, I will swap just the platter itself. I completed this process, carefully as usual, within a class-100 clean room environment. However, the drive is not able to calibrate and detect in the BIOS. The drive that was sent was a good working drive, but for some reason, this drive does not want to calibrate.

Any ideas what could be the problem with this particular case, and possible solutions that can be attempted to correct the problem?

From your statement, It seems the patient HDD is not only bad head but some other firmware malfuction itself.

You said the hdd was sent is a good working one.How do you know that? You detect it with software or it just works in PC?

Why not change the platter back and seee if it works?

I'd swap the other good (new) platter to the old cavity. I've often found that I can swap a donor head stack into a cavity and find it doesn't work. Then I take the patient head stack and put it into the donor cavity and it works fine. This tells me that the heads were okay--problem is elsewhere.

I've had quite a few of these problems - coicidentally almost exclusively with Momentus drives.

The problem has almost always been slight damage to the underside of the platter that you can't see so, when you replace the bad with good heads, the good heads get damaged as well.

To test this, I examine the heads under a microscope to check for damage, which is generally quite visible.

Removing and inspecting the underside of the platter invariably reveals the problem.