I bought a portable electric space heater a few years ago that had an alarming tendency to rewire itself - like, “Off” would become “Low”, “High” would become “Fan” etc. Finally took it apart and realized that the dial was just a contact that rolled across a bit of printed solder and occasionally the solder would melt (imagine that happening in a fucking heater) and flow into a new pattern. I have absolutely no idea why thousands of people haven’t burned themselves to death with these things.