Sash balancers - 531 or 737?

Question

I have the sash balancers removed from my Andersen windows. The number stamped on it is BJ 95#27 2 87.

From my research this 5#27 appears to be matched with the 531 part.

However when I measure the lower sash (visible glass) it is 21 15/16" high x 20 7/16" wide, which leads me to a 2042 size window which calls for the 737 part.

Please advise which part I need! Thank you.

Paul · Accepted Answer

Since your window was made in 1987, we advise going with our 24-531 Andersen Sash balance. The newer models have used heavier glass.