One note on the 7808 chips that the Runtz uses: it needs to have a load before it can properly regulate the voltage, so don't be surprised if the un-loaded voltage is higher (like 10-12V).
If you have a small-ish (500-5000ohm) resistor, put that between the output terminal and ground, then test at the output terminal and the voltage should be spot on at 8V.
If you see the 0V or 3V on the output without the resistor (like Jon said), that does mean it is le-dead (fancy french technical term).