Towards the end of September my alternator started behaving erratically. It charged correctly for 90% of the time but every so often the output dropped to zero for a few minutes before resuming again. (The ignition light warned me of a problem and the Battery Monitor confirmed what was going on) When I examined the alternator it was covered both inside and out with a very fine, reddish-brown dust. I removed the brushes (healthy) and cleaned a lot of the dust from them and from inside the casing where I could reach. I also cleaned the outside of the casing just to make myself feel as if I had done something. I put it all back together and it has worked perfectly ever since. Any ideas about what this red dust could be and where it has come from? I have had nasty, sticky black dust before from aging belts (I change them quickly if I find it) but this was not greasy, oily or sticky. Any ideas would be most welcome.