Seems more with a jab on the brakes, not mild application. Nothing seemed remotely loose in the headlight area. There was the one connector that I pressed/pulled on and it didn't move. Banging the assembly yielded no flicker. I could try banging it in the direction of travel to see if it's triggered by momentum of the assembly itself. At least I'm on to the start of being able to repeat it.

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Daily Drivers:
- 2008 535i, 320,000km
- 2004 X5 4.4, 01/2004 production, 420,000km
- 1997 328i, 350,000km

Track:
- 1996 328i, track/race car, ~300,000km

Winter:
- 2013 Ski-Doo MXZ X 800 E-TEC, trail can
- 2007 Ski-Doo MXZ Blizzard 800 HO
- 2001 Ski-Doo MXZ 600 w/800 engine, exhaust
- 1978 Ski-Doo Olympique 340 (vintage race sled)
- 1977 Ski-Doo Olympique 340E