NEW YORK — Wall Street extended its pullback yesterday as investors, retrenching from an optimistic stance early in the week, waited to see how well corporate earnings and the job market, whose report is due tomorrow, have held up in an uneven economy. The market showed little conviction for a second day as economic readings offered few surprises and as investors looked for signs of whether the market's rebound from its summer lows has been warranted. Wall Street had little reaction to a report that the nation's service sector, whose industries account for 80 percent of U.S. economic activity, showed a decline last month.