Invisible Spring Balances

A handy person from South Burlington, VT says:
Hi, I am just learning about my wood windows in my house (built 1968). The first floor windows all have these invisible side spring balances. the fine text on them says "Grand Rapid Invisible Spring Balance" (its hard to read). I have 10 of these windows with these spring balances. I'd like to try to replace the spring balances with something similar that works better than the current ones. Is that even possible?
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Paul from SWISCO responded:

We have a wood sash system Series 500 that has been used by wood window manufacturers since the 1940's. We will need the visible glass height and wood sash height for the top and bottom sash to select the correct Series 500 balance lengths. I placed some generalized directions that explains how to install this balance system.

For your wood lower sashes, you will need our Series 500 red tip balances with the 17-012 balance brackets. These brackets hook on the balance spiral. To install these balances, you would drop them from the top on the side of the sash. Use the 33-017 screw to attach the balance tubes at the top. Now, raise the sash and have someone hold it up while you attach the 17-012 with the 33-090 screw while the U-shape opening corrals the spiral. With your finger bring up the spiral to the bracket and attach the 75-005 charging tool and turn the spiral clockwise three turns and hook it to the fork of the bracket. Repeat the other side and try the sash. If sash creeps down, raise and hold up the sash and give the balances another turn or two.

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