ANDERSON WINDOW SASH BALANCE

Hard to read the number clearly, but looking at the photo of the sash balance (included above), it looks like R127827...??? The windows were installed when the house was built in 1989. They are wooden and just go up and down vertically. The bottom window has 3 rows of 3 panes each and the upper window 2 rows of 3 panes each.

I have a number of windows -- all the same -- that need their sash balances replaced and I just need to ensure I order the correct replacment parts...