Repair Stuck Sash & Broken Locks
Over time, old window sash gets painted shut; misaligned sash locks may break.
To break the seal of a painted-in window, insert a putty knife or 5-in-1 tool between the sash stile and the side jamb. Tap gently with a hammer and work your way around the sash. Have a vacuum handy for debris. Repeat on the window’s exterior. Shake the sash to see if it is loose enough to move. If not, place a pry bar under the stile and gently rock one side loose. (Work inside or out.) Repeat on the other side. Do not put the pry bar at the center—the glass will crack! Go back and forth on each side slowly until sash releases. Vacuum out channels and lubricate them with silicone spray.
Remove the broken sash lock and remove any dirt. Fill the old screw holes with wood putty. To avoid using the old holes, shift the placement of the new sash lock ¼" (any more than that and the lock will look off-center). Mark the location of the new drill holes, making sure that two pieces won’t catch on each other as the window is opened and closed. Adjust the placement as needed. Attach the top, non-moving piece first on upper sash, followed by the bottom moveable piece on lower sash. (If possible, have a helper hold the upper sash as you work.) Check that the lock “hook” moves smoothly and tightly into the latch and that the sash moves freely.