I have a Truth 40941-A Hinge that seems ok. However the end of the controller is broken.

I'm afraid that we aren't able to supply the broken end of that casement operator arm. What you have here is an older Roto brand part; we sell a modern version of the base, and we even sell a good alternative for the hinge, but that arm that connects the operator to the sash is discontinued. To my knowledge there is no substitute. 

I am very sorry for the inconvenience.