Well we all love to have bright shiny everything when dealing with engines. And for the most part it does help in so many situations. However, rust on coil laminated metal plates really doesn't effect their ability to produce voltage. It is the magnetic field that cuts across the windings that creates the voltage. So the answer is NO, the rust isn't really bothering the exciter coil. However, If it makes you feel better clean it up... I had solid rusted laminated lawn mower ignition coils that ran perfectly. But I had to clean them up anyways...that's just me! JMHO
