If the threads to the plastic knob have become damaged due to cross threading it will need to be replaced in order for the drag control to function properly.
There should be a spring over the shaft that is installed first, then the aluminum drag disc. In the top of the drag disc there should be both an o-ring and a plastic washer. The o-ring is inserted first and then the washer.
If any of these pieces are missing or installed in the wrong order the drag control system will more than likely not operate correctly.
If you are missing any of these items please reach out to us at firstname.lastname@example.org for assistance.