Darn shifter knob

They both come off together, what usually happens is they get screwed on to tight at the top, then when you go to loosen it, the cable just unscrews from the bottom instead of the top. Try to tighten it as tight as you can without breaking it then give it a quick snap to loosen and it might break loose at the top and come off. The cable does not come out but it screws into the knob and also into the lever at the bottom end of the shifter.