anderson window casement part c-9400-1a

That number is actually associated with a couple of different parts. I don't think it's one specific part number but more of a code on the molding. In order to identify the proper replacement, we'll need a photo of the original operator. Seeing it out of the window would be ideal, but if not then we at least need to see as much of it in one shot with as few obstructions as possible.

As for needing the adapter plate, it would depend on what year your window was made. If you can tell me that then I can confirm.

Thanks, Dave! This looks like our 39-099 Andersen awning window operator. Look it over and let me know if you agree.