CHICAGO Gannett Co. Inc. has an enviably low debt burden and online businesses growing at a healthy rate, yet even it cannot escape Wall Street's current aversion to newspaper stocks. The latest evidence comes from Morningstar Inc., the Chicago-based investment research firm. In its latest note from stock analyst Tom Corbett Morningstar lowered its "fair value estimate" of Gannett stock to $23 from $32 a share. It said investors should "consider buying" the stock at $17.30, and "consider selling" at $29.90. In afternoon trading Tuesday, Gannett (NYSE: GCI) was at $22.59, off 18 cents, or 0.8%, from its opening. It...