W164 Rear Light Cluster

[E55BOF]

The car is a 2007 W164. The left rear stoplight is not working; indicator, fog, reversing and brake lights are all fine. I took the bulb nearest the centre of the car out; it has not blown. Wiring, then?
So I Googled, and found this colour decode (on an American website:

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Brown: Ground

Black: Left Turn (12V)

Pink: Brake (12V)

White AND white w/ black: Reverse (12V)

White w/ green: Running (30% duty cycle)

Grey w/ black: Running (30% duty cycle) and Rear Fog (100% duty cycle)

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The wiring colours appear to be correct. I assume mention of duty cycles implies LED bulbs, but afaik my 2007 had/has normal 12V bulbs. That would imply that the white w/green wire is to a 5W bulb, and also feeds the 5W element of the rear 5/21W tail/foglight bulb. Before I start twiddling, does anybody know different?

 

[E55BOF]

Sorted; twiddling and a spot of fine wire brushing worked. No 5w bulbs anywhere...

I still don't see why it's the way it is, though. Both tail light bulbs in each cluster are standard 21w incandescents, but the outer bulb burns brighter than the inner one in normal running, so there's a resistor in there somewhere. .