Bests & Worsts Reviews from Amazon

I have an M570 trackball mouse that came with a unifying receiver. I've had it for about five years (longer than warranty), and it's worked great. Recently, though, the receiver has come loose in places and only works intermittently, so I bought this to replace it. I plugged it into my computer, went through all the steps, and it won't connect to the mouse. I tried everything, restarted the computer, tried every USB port, even called tech support (they said there must be something wrong with the mouse, which is untrue; the mouse will pair and un-pair with the old receiver till the cows come home). Then I noticed that the firmware was a more recent version with the new USB than the old one, and there was no way to update the old USB or mouse firmware. So now I have to get a whole new mouse and throw away a perfectly functional device, because apparently Logitech refuses to be backward compatible. So DO NOT BUY! There is absolutely no point. It doesn't work and never will. And to rub salt in that wound, it's also non-refundable.