I bought three of these small 4W "under cabinet lights" (W-mart, Lights Of Am...) Model 7104
I am annoyed to say that one bulb failed after a month and another after two months.
The filament is open on one side with a dark color on the bulb.
Replacing the bulb fixed the light.
I am trying to figure out why the filament would fail as I had these lights are on all the time (24/7 path lights to let me leave off the main shop lights)
I am tempted to take one of the lights apart to see if they used a "continuous run" capacitor type circuit to heat the filament using the main Square wave output.
Edit: Yes it does use a "continuous run" filament circuit just like the cheep CF bulbs.
I'll hook it up to the scope to see if I can add a Neon bulb starter to it.
Edit again: Nope. The light needs the filament to be hot in order to keep it light.