Actually, it's only flickered once or twice. The rest of the time it's just never done anything at all.
An inductive voltage detector claims there's voltage in the wires and bulb when the switch is on, and isn't when it's off.
I've checked the wires in the attic, taken the fixture apart, and taken the switchbox apart. It's got a 3-way switch even though as far as I can tell there's only one switch for it - but the other switch in the box is a 3-way as well, for the inside ceiling light, so I'm thinking maybe it's supposed to be that way. And of course I've swapped in new bulbs. Still no go.
The side of the fixture the wires connect to looks kind of old and grubby, and the wires don't look the greatest at that end. I'm thinking maybe I should take a voltmeter to the wires and see if things are up to spec, and if so, see about swapping in a different fixture.
Sound sensible to anyone? Any other suggestions?
Thanks,
-Dan