Saddled by debt from his acquisition of the Tribune Company media empire, billionaire Sam Zell may sell off the iconic Chicago headquarters of the Tribune newspaper, he said yesterday. The 83-year-old Tribune Tower could fetch $250 million, analysts told the Sun-Times, with Zell likely needing to assure a new owner that the newspaper would continue to occupy the building on a long-term lease to fetch maximum value. (More Sam Zell stories.)