Clean Weep Holes
Test the operation of the weep holes -- which drain excess condensation on the interior of the window to the outside -- by pouring 1 cup of water onto the interior sill track.
Insert a small wire into the small weep holes on each side of the lower window track on the outside of the building if the water does not drain from the sill in a few seconds.
Move the wire in and out to clear any debris or obstructions from the weep holes. Remove the wire and allow the water to drain from the sill.
Replace Broken Sash
Unlock the sash.
Press in or pull out -- depending on the brand of window -- on the release clips in the window jamb above the sash. Raise the sash upward until it clears the release clips.
Grasp the top rail of the sash with one hand and the bottom rail with your other hand. Slide the sash horizontally to one side so it clears the vertical track on the opposite jamb.
Rotate toward you the end of the sash that has cleared the jamb. Slide the sash horizontally out of the opposite jamb track. Remove the sash from the window frame.
Install the sash in the reverse order of removal.
Replace Balance Mechanism
Remove the bottom sash as previously instructed.
Pull down on the balance housing within the window jamb -- visible after removing the sash -- until it is free of the built-in clip.
Continue to grasp the balance and allow it to move upward until the balance attachment hook is visible.
Use a flat-blade screwdriver to pry the balance attachment hook from the window jamb. Remove the balance mechanism from the window.
Place the attachment hook of a replacement balance into the jamb. Push the balance downward until it engages the retaining clip.
Replace the sash.