As the shaft through the guts of the dizzy spins electrical spark is is sent up to the rotor button. Each time the dizzy spins past one of the electrodes on the inside of the dizzy cap it sends a charge through the cap to the lead and to the plug.
The rotor button is just a plastic hat that slides over the shaft tip that has a long electrode that comes out horizontally.
When cleaning the inside of the cap use a bit of wet and dry to clean it up but do not remove too much material or the rotor button wont contact properly and you'll be wasting spark inside the cap instead of sending it to the plugs. Caps arent too expensive. If your worried about cleaning it up go get a cap and rotor button.
Remember to clean out the cap properly and dont leave any dirt or metal inside the cap!!!! give it a sqirt with some CRC or WD to clean it out and remove any moisture.
If you want to dress up the inside of your engine get a clear cap. they cost a bit but but looks awesome!
Rivmasta