Remove the old channel balance from the window channel.
Fasten the top of the new S775 channel balance into the window track using a screw.
With the top of the new S775 channel balance fastened securely to the window track, carefully pull out the shoe approximately 8 inches. The shoe is attached to the block and tackle pully string at the base of the balance. You will feel resistance when you pull out the shoe.
Wrap the string around your finger to create slack on the string between your finger and the shoe. If the pressure is too much on your finger, use a pair of locking pliers instead. Warning: S775 balances made for heavier windows will have a great pull and it is a better idea to use locking pliers instead of your finger.
With the end of the shoe pointing up (see image), place the shoe into the window track.
After the shoe is in the window track, you can carefully let go of the channel balance pull string. Your shoe should fit into the window track as shown in the image. Make sure the shoe is about 2 inches above the window sill and then place your window sash back into the frame.