It's not exactly the pcb. GMR sensors (heads) are designed for signals in the picovolt range. Either you destroy something (i.e. the flex) or you damage the whole preamp. At PCB level the signal is pre-amplified and the preamp outputs are sufficiently "user-proof"

but at headstack level, it's not. When you remove the PCB (of course you do) you remove the ground connection between preamp and the rest... Have you ever worked with microwave cavities (gunn and schottky diodes) ? If the answer is YES... you know what I'm meaning.
I have a static free workstation and I have never had issues, and it's nothing "exceptional"... however, seagate drives are not a problem in transplanting HSAs, so I'm quite sure you do something wrong or use the wrong tools / instruments.