Nine years after staging Wagner’s complete Ring Cycle to international acclaim, Chicago Lyric Opera is reviving the production this week, and the team in charge of the staging is enjoying a rare opportunity in the opera world: the chance to review what does and doesn’t work about a particular production, and actually make the show better. “The performances are musical marathons, the final three operas running for more than 5 hours including intermissions. But Lyric has the benefit of having already performed it as a complete cycle three times, and many of the staff members and orchestral musicians who made that 1996 “Ring” so successful are still with the company.”