Hi all,
Just in case some bold technician flies over this thread looking for hints on how to DIY, I leave a couple of instructive URL's with images, that I condider useful for cases like the one I have in my hands (Hitachi 40GB Travelstar, clicking noise, bad head stack):
URL1 = practical view =
http://www.freewebs.com/bgotchall/index.htm (Hard drive platter transplant surgery for dummies)
URL2 = Expert view = Scott A. Moulton =
http://www.myharddrivedied.com/presenta ... paper.html (THE guide)
In my case, sequence:
1) The data is not that important, but worth to try a DIY, self-training data recovery
2) Other software method have failed (stellar, getdataback, mhdd, ...)
3) The symptoms (clicking noise) suggested a likely bad head stack
4) Bold phase start. Disk open. Long story short =
4.1) Platter reveals damage in negative cylinders, upper side.
4.2) There is something loose !! black and small = the bottom head
Next step: Await for my friend returning from vacations (it's clear I'm his friend

). My proposal for him will be: Look for a hard disk, same model, MLC, date, etc on EBAY; it's a bet around 30-50 dollars, and I'll try the head swap with this donor.
BTW: In this HD, it's a bit easier to swap (single) platter AND pcb (of course

) , instead of swapping the head stack. WHY? 1) Because this HD model has a parking ramp for the heads, and 2) Because Scot Moulton says that

Best regards (I'll welcome comments, criticism included

)