Natick (Mass.) Contributory Retirement System is searching for a core-plus fixed-income manager to run $18 million, said Kathleen Bacon, director. Officials at the $63.1 million pension fund want to replace the portfolio's current manager because of organizational changes, she said. Ms. Bacon and Kevin Leonard of consultant Segal Advisors would not identify the manager. Interested firms can e-mail [email protected] to obtain the RFP. Proposals are due Nov. 22.