Casement Operator

Need replacement operator. (actually need 3 if I can find the right one). Not entirely sure I can find this model on your website. All numbers are in the photo.

Arm that attaches to window = approx. 13 in.
Arms that attach to operator = approx 10.5 in.
Small arms that attach the above to each other = approx. 6 in.

The issue is that the screw mechanism that actually moves the arms strips (after 20 years). I bought a replacement locally 10 years ago, but the vendor is no longer in business.

Can you help?

James