Check if it's not a cord that fails.

how?

Mine just went too and It's the cord every time. Buy a new one., unless you can solder a spare cord on. You can't just plug in a new cord like you could with the ms 3.0.

where to buy the new cord?

I meant buy a new mouse.

I got a couple more years out of one of mine by twisting the cord and looping it inside the mouse. Try that.

i just ripped apart a black wmo just yesterday, seems to happen more on the black ones... have no idea, got so fed up with pulling the cable on it i dragged it by its cable and ripped it open, took the bottom and the top plastic and ripped it apart and threw it in the wall lol

the top piece is still laying on the floor :D

You don't need a solder, all you got to do is twist the cables.

The black ones always die first. Damnit! Why!?