1. First, remove the stop beads from the side of the window frame with a pry bar.
2. Pull the window out of the jamb and remove the tension hooks of the old sash balancers with a pair of pliers.
3. Remove the old sash balancers with a screwdriver or drill/driver.
4. Use a sander to smooth out the jamb and the edges of the sash.
5. To reduce friction, spray a lubricant on the jamb and sash.
6. Install new sash balancers by driving in screws into old mortises.
7. Attach the hook on the sash balancers to the sash on each side.
8. Reinstall the window stops on the jamb using nails and a hammer to keep the window in place.