Woburn (Mass.) Retirement System, with $70 million in assets, is searching for a domestic midcap growth stock manager to run 7.2% of total assets, said Gus Aristizabal, the Wainwright Investment Counsel consultant who is assisting. Proposals are due Sept. 21. The search follows the departure of the Babson portfolio manager who ran the funds domestic midcap growth stock portfolio. Babson will continue to manage more than half the funds assets in other portfolios. The fund also hired three real estate managers to manage $1 million apiece. They are TA Associates, Intercontinental Real Estate and Corcoran & Jennison.