I have a LEGO MINDSTORMS Robotics Invention System 2.0 (3804) that I acquired back in 2003 (17 years ago), and the wires have become grey and brittle.
The wires used to be black and smooth, and stayed that way for a solid 10 years until I stopped playing with this set in the fall of 2013. Last summer (July 2019), I got it out again for the first time in 6 years, only to find that the wires had become grey and brittle. I tested them, and they seem to be working, but I don't know how much longer that will be the case. At one point, I yanked on one of the wires a bit when detaching it from a motor, and it broke very easily. Clearly, even though the wires still work, they're not as versatile as they used to be.
Any ideas what caused this? Was it the long-term storage in the box? Was it that there hasn't been any current running through these wires in years? Or is it just inevitable that this will happen as the set ages? They've been in the box, sitting in a room at room temperature for several years.
Has anyone else with an old RCX-era MINDSTORMS set experienced this problem? Any suggestions on what can be done to stop or slow the deterioration of these wires, or perhaps even reverse the effects? It would make me sad if I couldn't use this set anymore. I had a satisfying fill of fun with this set from age 6 to 16, but I'd also love for my future posterity to get to enjoy it.