The decision and plan to find a buyer is noteworthy because the Journal Register — whose collection of local publications includes the New Haven Register — engaged in one of the most ambitious efforts by a newspaper owner to chart a new path in the digital world. It went bankrupt once before following an acquisition spree, and emerged as a private company in 2009. ImpreMedia co-founder John Paton became CEO. He assembled an advisory board that included digital journalism evangelists Jeff Jarvis, New York University’s Jay Rosen, and Columbia University’s Emily Bell. Alden Global Capital, a hedge fund that specializes in distressed newspapers, bought the company last year. Despite several experiments to slash the price of newsgathering and production, Paton says today that the digital “transformation is threatened by a decline in print advertising revenue — the Company’s largest revenue source” as well as costs such as pension liabilities that were baked in when Journal Register was much bigger. Although the company “cannot afford to halt its investments in its digital future it can now no longer afford the legacy obligations incurred in the past,” Paton said in a note to staffers. He says the company will continue normal operations while it conducts an auction, expected to be complete in about 90 days. It filed for protection at the U.S. Bankruptcy Court for the Southern District of New York.