I've had the same Ka-click sound with my dead 3 month old Lacie external drive (you'd think these days most things would last more than 3 months). TechTool says that its a hardware problem which it cannot fix. Having spoken to Lacie they reckon the drive is dead & told me to return it for repair but couldn't guarentee the security of the data, if it was retrievable.
Having been told to return it to the vendor I got in contact with Play.com, not the best place for computer hardware but it had the best price. Unfortunately they won't touch it as it has been taken out of the box, even when I point out that it is within its warranty period and all they need do is send it onto Lacie. Lacie won't take it direct but won't get in contact with Play.com.
That's 2 companies I will never be using again!