This article might not look like much, but I highly recommend that you mess around with the red and green plastic anyway. Sometimes your machine will attract a sharp, conductive dust mote which then spews charged wind. This presents major current leakage and partially shorts out the sphere voltage. With luck, wiping down the sphere will dislodge it. Under high-humidity conditions, insulating surfaces can behave as a dead short, almost like metal, even though their resistance remains too high to easily measure.
Electrostatic effects deal with high voltage at little or no current.
Because the voltage is high and the current low, even a fairly insulating object can act like an conductor when used with electrostatic devices. Ohm's Law tells us that high voltage at low current implies high resistance. For normal, non-electrostatic circuitry, low voltage at high current implies LOW resistance. If the source-impedance of an electrostatic generator is ten billion ohms, then any material having much less than this resistance will act as a good conductor, while materials having much more resistance will be insulators. A dirty surface in a humid environment might have hundreds of millions of ohms across its surface, yet it will act as a good conductor and can short out your generator.