Eureka, I found it!

Actually, my husband found it--the missing wire for our urn had fallen behind the microwave.  (Apparently, I'd "stored" the wire on top of the microwave, rather than doing the intelligent thing and stashing it inside the urn.)  As of this week, we'll be back to heating hot water on Friday afternoon for pre-brewed tea on Shabbat.  Yay!  The apartment very slowly returns to normal, now that the renovations are almost complete.