Replace the sash in a Pella window by first removing the sill cover to access the sash. Unscrew the sash and replace it before setting the window’s sill cover in place.
Pop the screen off the window to gain access to the sash operator. Gently run a razor knife against the sill cover at the point where it connects to the windowsill. Open the Pella window to provide space for you to remove the sill cover.
To remove the sash handle, unscrew the stop-screw that lies on its lower part. Gently remove the sill cover by nudging its underside with a pry bar. In case there are some nails left hanging upon removing the sill cover, get them off with a pair of pliers, claw hammer or wire cutter.
Remove the screws that link the sash to the operator, and then detach the sash from the windowsill by unscrewing its holding screws. You can then install a new sash at the same spot as the old one to avoid misalignment. The sash screws should also fit into the original slots on the sill. Check to ensure that the Pella window shuts properly once the replacement is complet, then replace the sill cover.
Replace the sash cover and the handle. Once the sash operator is working properly, replace the screen.