UPDATE: the tech came out the next day and removed the refrigerant, installed a tap and recharged the system with fresh refrigerant. His reckoning (and that of others with great experience) was that the capillary tube got blocked after the defrost timer malfunctioned.
Once he purged and recharged the system, it started working normally. Within just a couple of minutes (while we were talking) the freezer section dropped to 28 degrees and the fridge was also well on its way down.
A few hours later, the icemaker dumped its first load into the bin.
And both sides of the refrigerator are now working normally. This morning the tech called and double-checked with me, unasked, to verify that everything's back in order. Great customer service!
We're all happy to have the thing back to normal!
