I hoped this bit of roadside debris would yield a shiny new amber LED and driver:
But, alas, it uses an ordinary WY5W incandescent bulb:
That whole assembly seems to be the replaceable unit, as the lens is firmly snapped-and-glued to the housing. The white shell used to hold the wires, but those vanished when the collision ripped the mirror off the car.
After I pried off the shattered lens and extracted the bulb, I found a broken filament.
Ah, well, now we won’t be riding through plastic shards along the shoulder.