Joann,
Most people don't know they can do most everything electrical. It is simple
and safe when you practice care. It is not rocket science. Your light
fixture can have a loose base where the bulb screws in, because people just
have to continually over-tighten every bulb. Done often enough, it pulls and
bends the socket. When installing any bulb, you should turn on the light
before final tightening. When the bulb begins to light, stop turning when
it's just barely firm. All bulbs, including spiral florescent get hot or
warm. Heat expands and further pulls at the socket base.
Your lamp, like the yard lamp, will have all the black and all the white
tied each tied each set together. Just one of the wires getting a poor
connection, will feed the one problem bulb too much voltage because the
other two set up a transformed capacitance voltage and the lost ground bulb
is seeking a better connection. The connection is there, but not there. You
cannot ignore simultaneous devices working on a single feed. It's just an
overlooked simple physics occurance.
This is why a lost ground on your turn signal bulb, won't light that bulb,
but make all the other bulbs blink faintly or even brightly.
I am sorry to be so wordy. I can help you solve your simple problem with the
living room lamp.
-Eddie- Houston