Truth Casement Handle Replacement
Thanks for posting. It does appear that either our 39-375 or our 39-376 should work as a replacement but you may want to confirm that the measurement for the base of the operator is a match. (The one you have pictured is our 39-375.) Take a look at the diagram below to use as a reference.
I took the handle off so you could see the stem.
Okay. I see now, your operator cover and handle cover are separate from one another and it appears your cover is not removable.
Take a look at our 39-205. It is a folding handle and should work for your crank operator since it is a Truth Hardware product. If you are needing to replace the stem, you'll need to replace the entire operator.