Looking for correct part

Thanks for reaching out to us! I'm afraid the operator's arms are too obscured to make out. Can you show us a full view of them with the window completely open? That will allow me to get a better look and narrow down some options. 

Thank you! This is a huge help. I recommend you have a look at the 39-439B and 39-253RB operators. The best match will ultimately depend on the guide used at the end of the arm. The video below will explain what I mean. 

We also sell the 39-452 cover and handle in case you needed that!