Reuters Taiwan's TSMC, which is making an unprecedented push into chip manufacturing overseas, is taking an increasingly optimistic view of Japan as a production base, two industry sources said, as problems persist at its new factory in Arizona. TSMC, the world's largest contract chipmaker, is frustrated in Arizona, the sources said, where it has struggled to recruit workers for the gruelling chipmaking trade and faced pushback from unions on efforts to bring in workers from Taiwan. The company has growing confidence in Japan, where an $8.6 billion fab under construction in a chipmaking hub on the island of Kyushu is…