Items you will need
Epoxy wood filler
¼ inch hooks
Replacing the spring system on a window is a simple process, but will only work if the window has a wood jamb. If the window frame is made of metal, you will need to contact a window installation professional to change the spring for you. Window springs wear with age and over time it may become difficult to open your window. Changing the springs should only take about an hour and will make it easy to open your window again.
Find the stop bead located on the thin wooden sash along both sides of the window. Use a utility knife to cut the paint so that it is not damaged when you pull the wooden frame away from the window during spring replacement. Use a screwdriver to unscrew the stop bead from the window. Remove the stop bead and set it aside.
Locate the side jambs on both sides of the window. They should be just under where the stop bead was located. Cut the sash cords holding the window up, if there are any. Gently pull the bottom sash of the window away from the top half of the window and set it aside.
Remove the old spring system from inside the sides of the window. Use a screwdriver to loosen and remove the screws, then pull the unit out from the wall using pliers or a flathead screwdriver.
Weigh the window sash on the bathroom scale to make sure that your replacement springs can carry the weight of the sash. The packaging for the springs will clearly state the weight limit for each spring. If you are unsure of the weight support you will need for your window, then wait until you have weighed the sash to purchase the replacement springs.
Fit the replacement spring into the hole left by the previous spring system. If the hole is too small then use a forstner bit attached to a handheld drill to widen the slot on the window jamb. If the hole is too large, then fill the top of the hole with epoxy wood filler to make the hole smaller. Let the epoxy dry for 24 hours before installing the new spring.
Fit the new spring into place and screw tightly against the window jamb with a screwdriver. Attach the spring line or tape to the old hole along the outside edges of the window sash where the cords attached to the old spring system. Screw a tiny hook just above the hole to give the spring line extra grab.
Apply lubricating paste to both sides of the window sash to make it easier for the window to raise up and down. Hook the spring tape to the hooks installed on the sides of the window sash. Push the sash into place against the window jamb.
Replace the stop bead on both sides of the window.