Yes, I did mean stop/FAIL; just for information if anyone has a fail, it can possibly be fixed.
A couple of months ago, I installed a LED side/city light, and LED stop tail (6V, -ve earth).
The tail light looked a bit dim in the daylight, but ok in dark, figured that is normal.
When out I often check the lights working but other night coming back from somewhere, no tail light
When I got home, tried first option- give it a tap, and it flickered. OK it has life.
I figured it must be the contacts in the holder, so built them up with solder, and when I put the bulb in it seemed loose, turned out the LED unit had separated from the base.
I resoldered it, but still no joy.
Turned out that the resistor tail inside had broken off from the 4 pole chip. Jaycar didn't have a 7.5Ω, so used two 15's in parallel....all is now hunky-dory, and as bright as I'd initially expected in the daylight.
(fyi- The resistor in shot is the brake one, it's 1Ω, and the diode isn't burned, just some dust on it.)