Problem solved. After conversations with Elecraft support, I pulled
the front panel from the radio and checked the connector pins. All
looked OK and none was bent. I removed the DSP board and reseated it.
Following reassembly, digi functions worked correctly.
I rechecked my Cocoa Modem settings on my MacBook as well as Menu and
Config settings on the K3 to confirm all were correct. Next was a
PSK31 QSO to Scotland.
Thanks to all who offered suggestions. I'll file them away for future