How to Repair Block & Tackle Balance on Andersen Windows

Unlock and raise the lower sash a few inches. Flip down the wash assist tabs on the lower vertical side of each window jamb.

Press inward on the sash release buttons on the top edge of the lower sash. Rotate the sash towards you until it's at a 90-degree angle to the window frame. Hold the sash in this position.

Push in on the release tab on the sash pivot pin in the window jamb on one side of the window with a flat-blade screwdriver. Lift this corner of the sash a few inches until it clears the release tab. Repeat to disconnect the sash from the release tab on the opposite side of the window. Remove the sash from the window frame.

Slide the wash assist tabs to the top of each window jamb. Lower the upper sash a few inches. Push in on the plastic jamb liner on the right side of the sash. Pull the sash towards you. Push in on the left jamb liner and rotate the sash downwards. Push in on the release tabs in the jamb to remove the sash from the window frame in the same fashion as the lower sash. Skip this step if you're only replacing the block and tackle balance mechanisms on the lower sash.

Release the tension on the balance mechanism you wish to replace by inserting a flat-blade screwdriver into the cam near the release tab on the right jamb and turning it 90 degrees to the unlocked position. Leave the screwdriver in place and let the tension release from the cam slowly. Remove the screwdriver.

Disconnect the outer edge of the jamb liner on the chosen side of the window by grasping it near the window sill. Place your thumbs in the upper sash track and compress the liner slightly to blow it out. Work up the length of the liner until it's released from the window jamb. Remove the liner from the window frame.

Pry the balance assembly out of the pocket in the jamb with a flat-blade screwdriver. Pull the tab from the balance cord from the balance assembly. Push the tab into a replacement balance assembly. Push the new assembly into the pocket on the jamb until it's fully seated.

Squeeze the ends of the sash liner to bow it out slightly, then snap it into place on the window jamb. Insert a flat-blade screwdriver into the cam and push it downwards until the cam is a few inches from the sill. Turn the cam 90 degrees to lock it into place.

Install the window sashes in the reverse order of removal.