i have a few western digital drives (40eb), all tests ok, after a few hours of work they click and enter busy state for a short time (they turn off and on without recalibration).

in time they develop fake bad sectors.

interesting is that when i do surface scan, even after a few minutes from start, and i touch the drive with bare hands they do the same thing. if i touch them with something else, nothing happens.
i know that wd's are very sensitive to statics.

do you know if that is a pcb or firmware problem.