City of Medford (Mass.) Contributory Retirement System is searching for an active domestic high-yield fixed-income manager to run $6 million, said Thomas Curtis, chairman of the retirement board. He would not identify the portfolio's previous manager, saying only that the board of the $125 million system decided to move in another direction "after careful due diligence." The board will likely make a selection by the second quarter. Martin Coughlin, senior analyst with consultant New England Pension Consultants, did not return a call seeking comment by press time.