Milgard dormer

Hello,

It looks like you may be showing part of the operator that moves the sash. If you could show us the base on the inside of the window, we can go from there. Thank you. 

The track shown in your photos resembles the Roto 39-543. We no longer carry it and it may no longer be available. With that being said, take a look at the 39-440B operator, along with the 39-512 track. This operator has a longer arm than yours but look it over to see if you could adapt it to work for your window. The body itself is also wider than your operator so you'll need to make the cut-out in the window wider to fit your frame. 

Dimensions for 39-440B

Alternate view and dimensions for 39-440B

Alternate image for 39-512

Close up view of the channel guide end

Take a look at the related items on this page to see if you could use this hardware for your repair. If not, your best bet would be to contact a Milgard supplier in your area to see if they still have this original hardware.