"Peter" wrote in message
...
I've got a "no-name" clamp-on fluorescent lamp that no longer starts when
the rocker switch is snapped from the off to the on position. The lamp
has a polarized plug with an in-line black "brick" 7 1/2" x 2 1/2" x 1
3/8" that has the code "G0138" stamped above the code "GG10051F" on the
bottom but no other markings. The 2 conductor cord from the brick goes to
the base of the lamp where the clamp is located. The lamp uses a single
18W 4 pin double tube bulb with code G24q-2.

I'm sure that the bulb is good because I have a second, identical lamp
(that works normally) and when I swap the bulbs, the "good" lamp works
perfectly with the bulb from the lamp that is not working. I also have a
brand new spare bulb that I've tried in the non-functional fixture and it
too fails to light in the bad fixture.

The problem started spontaneously with no earlier indication of problems.
Normally, when the lamp is turned on, there are a few quick white flashes
in the bulb and the bulb lights and glows steadily. The behavior I
observe is that when I snap the rocker switch to on, the bulb either has
one quick white flash but then I only see the heaters glowing in each of
the two tubes, or there is no white flash at all, and all I see is the
glow of the heater filaments. I've tried plugging the lamp into another
outlet in case the problem was related to grounding (I've read that these
quick start bulbs need their circuits and fixtures to be grounded to work
properly) but it did not help. The "brick" has always been entirely quiet
and never got particularly warm, and that has not changed.

Any suggestions (besides ditching the lamp)?

I think that what you're calling the "lamp", what I would call the fixture,
has a bad ballast transformer. If it is integral to the fixture, it's
probably not worth trying to replace.