Thanks for posting! Since the gear worm in the operator has come completely dislodged, you'll need to replace the entire casement operator. There are few different types of operators we have compatible with the cover and handle you have here.
I'll need to see a photo of your entire operator to determine the exact replacement recommendation.
Thanks for the photos, they help a great deal. Your casement operator looks like it could be our 39-031. Look over the dimensions and compare them to your existing operator to confirm that this is the replacement you'll need.
The compatible cover is part 39-107 the crank handle is part 39-114L.
Take a look at part 39-155. To measure the longer piece, you'll have to uninstall it to get the full measurement.
It is more likely that it measures 10-3/4" from the center installation screw, as shown below.
