When my office received a call inquiring about flickering lights in a 1960's rambler, I had a pretty good idea what might be the problem. I got out here the next day and immediately went into the garage. It was no surprise to see a Zinsco breaker panel that been installed like in many other Seattle homes in the 60's. Removing the cover I was able to see that some of the breakers were loose on the buss bar. They had the panel replaced within a week.  I had them save the panel after it was removed. The breaker had been arcing and losing contact, a common problem with these panels. The photo show the scorch marks and another with a cracked housing.