This shows the Zinsco main circuit breaker box and the thermal image of the bad breaker. According to a number of Youtube videos the Zinsco breakers and box are problematic and potential hazards.
One leg of the 240 volt supplied to the house is causing flickering lights--i.e. the 120 volt leg is intermittent. The lights went out for more than 5 minutes--allowing me to measure the voltage dropping to zero.
Here are pictures of the pedestal with the meter and connections to SDGE main power plug.