New operator doesn't connect to the sash

A quick learner from Illinois says:
I bought the 39-312 awning operator, but:

Attached are pictures of original (brass) vs. plastic that was received. The plastic slider does not fit into the window track - it is too wide. The brass plate is 2 3/4" long by 7/8" wide.
Your assistance in identifying the correct replacement part is appreciated.

Thumbnail of the uploaded file named operator arm brass attachment
Thumbnail of the uploaded file named operator arm brass attachment
Thumbnail of the uploaded file named operator arm brass attachment
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Emily from SWISCO responded:

Hello!

Thanks for reaching out to us. I'm afraid we don't sell an operator that uses the same brass guide shown here. However, the 39-312 you purchased is compatible with the 39-512 track which we think is worth considering. Have a look at the specifications and see what you think. 

Alternate image for 39-512
Alternate image for 39-512

Close up view of the channel guide end
Close up view of the channel guide end

How to identify casement and awning operators
How to identify casement and awning operators
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