If this is your board …
http://www.ioffer.com/img/item/124/401/351/NJyplYi3jIDcWt9.jpg
… then my understanding is that the Marvell MCU often develops a fault that mimics a head or media fault.
Therefore, even though it does sound like your drive has internal problems, you should first try a board swap (plus U12 transfer).
Also use a soft white pencil eraser to lightly remove any oxidisation from the 20-pin preamp contacts at J1 (top left corner).
