Thanks guys! (And nice cars!)
I looked up the part number for both of your cars, and it seems to be the same as mine, i.e. 124 820 05 01. So it seems like all 3 of ours should be the same, I guess 2 of ours are burnt out? Can't imagine that it would be different only for the coupe.
That part number is unfortunately for the whole dome light housing base, which includes the 4-position switch.
When I pulled mine, there was no lamp external to the switch, so it must be inside somewhere. It does look like the back will come off the switch, but there will then be various loose/sliding contacts.
I'm going on a road trip in a few days and will probably wait until afterward to keep obsessing about it. Maybe JCE will have the guts to try replacing his in the meantime?
Fastlane shows the part at $73.87, which makes for an expensive bulb replacement if the switch kibbles 'n' bits don't go back together.