Key problem with BlackWidow v4 x.

Hi, I was given this keyboard today (it seems to be second-hand). The problem is that the W key worked fine, but after a while it started malfunctioning. It doesn't respond every now and then, and I have to press a little harder for it to register. Even when I hold it down, it suddenly stops responding. I've tried everything: updating drivers, cleaning the keyboard, unplugging and plugging it back in, and even restarting it, but the problem persists. I read here that the switch is probably damaged, but how do I repair or replace it? Or should I just throw it away?