Many ceiling lights and ceiling fans operate on a pull chain switch. Over time and with constant use, these chains break down or get stuck. The best way to remedy this situation is to simply replace the whole pull chain switch. With the right tools and know-how, this is a job fit for any competent do-it-yourselfer.
Cut the power to the room where you will be working at the circuit breaker or fuse box, flipping the breaker or pulling the fuse. Never work with electricity that has not been turned off.
Remove all covers and accessories from the light fixture, including all light bulbs. This allows unrestricted access to the fixture itself. Some accessories are screwed on and can be removed with a Phillips-head screwdriver.
Remove the end cap by turning it counterclockwise and pulling it over the chain and off the light fixture. Locate the wire connections from the pull chain switch to the light. Disconnect the wires and pull out the switch.
Replace the old switch with a new pull chain switch and replace the end cap back onto the light fixture.
Reattach the wires from the switch to the light, black to black, ground to ground. Wrap electrician's tape around the exposed wire ends and push them back into the light fixture.
Reattach the end cap and put back all lights and coverings. Turn the power back on to test the new pull chain switch.