The dealership looked at my radio which had recently refused to release a
cd.

They disconnected the power, reconnected it, and the cd ejected
automatically.

So it appears at least at a first approximation that the problem is with the
eject switch itself, which is what they said it is. Of course it could be a
deeper error in the circuitry, but there is no real way to know.

Is replacing the switch itself something that can be done easily?