BSI balance, mid 1980s

Hello!

It looks like you may have a tilt window channel balance but I can't tell what you need from these pictures alone. Can you remove an undamaged balance with the end fittings intact and show us some pictures? I've attached some videos below that you might find helpful. Take a look and let me know if you have any questions. 

For these balances, you will need our Series 751 ribbed channel balance with the 15-014 knife shoe attached.

For the balance stamped "20 BSI", see our S751-21 with a 20R spring strength option. 

For the balance stamped "28", see our S751-29 with a 28R spring strength option. 

For the balance stamped "36", see our S751-37 with a 36R stamp option. The short S-clip is the 15-029 and the long S-clip is the 19-030.

Before you remove the wood trim, try this. Raise and grab the bottom sash and pull the sash top out towards you from the jamb liner (like a tilt window). The vinyl jamb liners usually have some type of spring mechanism pressing against the wood sash. Twist the sash to unhook the pivot bars from the knife shoes and then repeat the process with the top sash. With the sashes out, cut away any paint from the wood trim and vinyl jamb liner. Now you should be able to remove the vinyl jamb liner from the window frame. Lay the jamb liner down and slide the balance from the jamb liner through the top where the S-Clip is. To install the new balance, hook the S-Clip on the top rivet of the balance. Slide the knife shoe, the 15-014, first in the jamb liner with the balance and hook the clip at the top of the jamb liner. With a flat tip screw driver, press down the metal knife to loosen the shoe about 12" and lock it in the track. Repeat for the other side. 

You will notice the bottom sash balances use the long S-Clip, our 19-030, and the top sash balances uses the short S-Clip, our 19-029. Place the jamb liner in the wood frame and install the top sash first by twisting the bottom to attach the sash pivot pins to the knife shoes. Swing the sash up into the jamb liners and raise it just about three inches short from the top. Now install the bottom sash in the same matter. Now you can fully raise the top sash and fully lower the bottom sash.