Waltham (Mass.) Contributory Retirement System is searching for a manager to run $9 million in active domestic midcap growth equities, said Joseph Juppe, executive director. The portfolio will be benchmarked to the Russell Midcap Growth index. The $130 million plan initiated the search because the existing manager, which he declined to identify, has not met performance expectations. Matthew Seney, senior analyst with consultant Wainwright Investment Counsel, also declined to name the existing manager but said plan officials could reconsider the firm in the search. Mr. Juppe said he thinks plan officials will select a manager in late February or early March.