A handy person from Winter Springs, FL 32708 says:
January 25, 2017
The window does not operate satisfactorily due to left side balancebottom shoe broken off. Measured length to be 31". Width 9/16". Stamped in balance "3010". See attached photos how do I order a pair of replacement balances?
Paul from SWISCO responded:
February 1, 2017
Please see our Series 377 channel balance, this appears to be a good match.