If you are able to fix the operator, you should also either replace your springs, or adjust them. When parts start going out of your operator, typically it means that your springs aren't doing the work that they should. In other words the operator just replaces your arm for opening the door. Call the overhead door of KC store in KS. I think Frank still works there and if they have the part, he'll be able to hook you up.
I used to be a salesman for OHD for 5 years.