I've been there two years ago... until now (when I finally have everything in duplicate), I was freaking out at any suspect sound from inside the PC casing.
Let's see the SMART readouts first.
Also, do keep in mind that there's also the possibility that the drive's circuit board is on the fritz. They're theoretically replaceable within some restrictions, altough the process may require someone with fine soldering skills to transplant the old drive's ROM chip to the new PCB.
If your "pro" has access to a class 1000 (ISO 6) or better clean room, and an identical drive can be acquired, then there's a slim chance of salvage through a rather extreme procedure (which should be saved for absolute last ditch, both because of the expense and the risks involved).
Bottom line: It ain't dead until we run out of options.