Update: I performed all the tests that Ronald suggested, and the rig passed all of them! The buttons showed all of the proper voltages at pin 26 when each was pressed. R44 and R45 values were also confirmed.
The problem still persists, although I did find several less-than-perfect solder joints along the way, which I've cleaned up.
I've ordered a replacement IC2, which is scheduled to arrive at my house this week, along with a couple of other QRP Labs kits to justify the shipping expense. Fingers crossed!!
