If your's has the barrel set screw, it is removable with jeweler's screw driver. Loosen it, then carefully pull the knob out and the barrel set screw will fall out the front when you tip it. Be very careful to put a sheet or something else underneath it, because if you lose it to my knowledge no one sells just the set screw anymore. Mopar parts guys will gouge you $40 for two knobs and two set screws (the second one is for the clock).