Examine your window along the sides above the bottom pane. On wood windows you should see ropes on either side. You may find one rope or no ropes. If you have no ropes, check for counterweight pulleys in the jambs of the window. Windows without these are gravity operated and, therefore, unable to be adjusted.
Remove the casing on the side of the window by prying it away from the wall with a pry-bar. Pull the nails through the back of the casing to preserve the face with locking pliers and set it aside for reuse. Repeat on the opposite side. Lift the counterweights from the space behind and remove the rope ends from them.
Remove the inside stop on the window jamb. This is the flat trim running up the side of the window, in front of the lower sash. Pry it loose with a wood chisel and hammer. Pull the nails through the back of the trim with locking pliers.
Lift the sash from the window and remove the rope ends, if any, from the grooves on the sides of the sash. Cut new 1/2-inch cotton poly-blend rope long enough to reach from the bottom of the sash groove to the top of the weight, resting in the bottom of the weight well, when the window is in the up position.
Knot one end of the rope and slip it into the end of the groove, run the rope up the groove, feed it through the counterweight pulley, pass it through the ring on top of the weight and tie a knot. Repeat on the opposite side and set the sash back in place. Replace the stop and casing, nailing them with finish nails.
Aluminum, Steel and Vinyl Frames
Examine the window jamb. Metal frames should have a flat metal strip running up the frame on either side. Windows with no spring depend on gravity and cannot be adjusted.
Remove the screws from the inside window stop and lift it from the frame on both sides of the sash.
Lift the sash out of the frame and move it up and down to see if both springs are rolling in and out. Remove the sash by unhooking the spring from each side of the sash.
Remove the screws in the jamb on the face plate of springs that do not function or move slow. Lift the spring cassette out and replace it with a universal spring cassette.
Reattach the sash, lift it into place and replace the inside stop. Tighten the screws in the stop to complete the job.