How to replace an Andersen® casement window operator

Read these steps before you start. This guide is for Andersen® primed wood casement windows made from 1932 to 1989. Crank operators and wood sills changed over those years, but the replacement sequence is the same: open the sash, free the sill cover, disconnect the shoe, swap the operator, then put the cover back.

The primed wood casement line is discontinued. Most operator and handle parts are still available. Shop casement operators or send a photo if you are not sure which years you have.

Painted or stained sills: score the paint or caulk line with a sharp razor knife before you pry. That keeps the finish on the surrounding wood from tearing.

Which operator era you have

• 1936–1974: straight-arm operator with a metal base.
• 1974–1979: plastic snap-on cover with no screw holes in the cover.
• 1979–1988: plastic cover with two extra screw holes. Those added screws help hold the operator steady.

A replacement operator may arrive with the current cover (holes for extra screws) even if your original cover had none. That is normal. Use the same screw holes in the sill that the old operator used.

Remove the old operator

1. Crank the window open

Open the sash fully so you can reach the sill cover from outside and see the operator shoe in the sash track.

Watch the weather. Wind can catch an open casement, slam the sash, and break glass — or worse. Have a second person hold the sash if it is breezy.

2. Free the wood sill cover

From the outside, pry gently on the underside of the sill cover. On painted units, first score the paint or caulk line so the cover separates cleanly from the sill.

If you cannot see the joint, press lightly on the underside of the cover. A faint stress line shows where the two pieces meet.

Slip a flat putty knife under the pry bar so you do not dent the wood. Work the cover loose all the way across before you lift it off. The cover is thinner where it sits over the crank. Do not rush, and do not lever in one spot only.

Too much pressure can split the cover. Old sill covers get dry and brittle. If a piece starts to crack, stop and work from the other end.

3. Disconnect the operator shoe

The operator arm ends in a shoe that rides in a track on the sash. There is a notch in the center of that track. Align the shoe with the notch, then lift it out. You will use the same notch to reconnect the new operator.

After the new operator is in, a light coat of silicone spray on the track helps the nylon shoe glide. Do not use grease that will collect dirt.

4. Take out the operator screws

Older windows often have a plastic cover with no screw holes. You can sometimes leave that cover in place, but check underneath — hidden screws are easy to miss. Newer covers have two holes so you can drive extra screws through the cover into the operator for a stiffer mount.

Remove the screws and lift the operator out. Keep the old unit until the new one is in, so you can match arm length, shoe style, and handing.

Install the replacement

Reverse the removal steps. Set the new operator on the same screw holes, drive the screws, then clip the shoe back into the sash-track notch. Cycle the crank with the sash supported to confirm the arm travels smoothly.

When you put the wood sill cover back, pull the old nails through rather than hammering them back the other way. Driving them reverse usually splits the wood around the hole. Ease the cover into place and set two or three finish nails to hold it.

Confirm the part before you order

Match handing, arm length, and shoe (square nylon, round metal, or triangle) to the operator you removed. Parts and Hardware stocks Andersen® casement operators and crank handles for these windows. If the stamped numbers are worn off, send a photo of the old operator and the sash track to the Kansas City team.