It's Milgard Casement window

Thanks for your post! I believe we can supply a replacement for this window operator. Although, to ensure we are provide the correct match, I'd like to see a photo of the end of the operator arms (detached from the sash) and the operator base.

Please let me know if you have any questions!

Your awning operator is a match for the 39-239C Ss Encore Awning Operator. This version is stainless steel which may help with the rust and corrosion. 

Carefully review and compare the dimensions to confirm that this is the correct replacement. The compatible hardware and accessories can be viewed below.

DImensions for 39-239C

Alternate view and dimensions for 39-239C

Alternate view and dimensions for 39-239C

Happy to help! Please don't hesitate to reach out with any additional hardware repair projects you might come across.

Have a great day.