I managed to get the task half-finished before I had to knock off for the day to attend to something else. First, I removed the driver's side vent, which indeed provides better access to the switch. Then I unplugged the wiring harness connector from the back of the switch and had just enough time remaining to loosen one of the set screws (see photo). Even with access through the vent, getting a small screwdriver on those screws is a challenge, I kid you not. Wrapping things up will have to wait until tomorrow. I hope it's not a godawful thrash to get it back together.
