I need 2 replacement Andersen window balancers like the one in the picture. The part number stamped on the defective unit may not be very clear but it is D47 8P31 277. The units are used in a window with 2 - 28 by 28 inch glass panels.
Tom from SWISCO responded:
April 25, 2016
Based on your stamp, I recommend our 24-837 Andersen sash balance.