Hey there,
Thanks for posting! Your casement window operator reminds me of our 39-342 Roto Dual Arm Casement Window Operator and its opposite handed version, 39-341. To confirm that this is the correct fit for your repairs, take a look over the dimensions below and compare them.
The compatible handle is the 39-232 Roto Folding Crank Handle. I've also linked a few of the other compatible hardware components below.

Alternate image for 39-342

Side profile view with measurements