Lamps have a variety of switches to turn them on and off. One of the most popular ones is the rotary switch. The rotary lamp switch consists of a threaded stem to which a plastic knob is attached. The other end of the threaded stem connects to the switching mechanism inside the light socket. Many times the on/off knob of the rotary switch may become stripped or cracked and need replacing. Replacing the on/off knob on a rotary switch is completed in less than a minute.
Unscrew the old on/off knob from the threaded stem part of the rotary switch. Turn the knob counterclockwise to loosen and remove it.
Take the old knob to the hardware or home improvement store to ensure that an identical knob is purchased. The knobs are available in a variety of colors and styles.
Place the open end of the knob over the threaded stem of the socket and turn it clockwise. Ensure that you screw the knob straight onto the stem to avoid cross-threading. Keep turning the knob until it operates the on/off mechanism of the switch.