I lucked out and bought three (original) MX518 on clearance at a Target after they were being phased out in favor of the (inferior) original G5 laser mouse. I gave two away as gifts, but the spare lasted me many years. Technically it never stopped working, but I wanted to try out the newer models and their nicer cables and teflon sliders. When the remade version came out, I bought one and when I realized how much better it was than my Tron-like Logitech mouse they has been pushing, I bought a second one so that I could hopefully go decades until I needed to worry about this. That backup new MX518 is still in the box, so my plan has been a complete success.