Paul,
While both LEDs on the socket were illuminated, a second (and third) look and some probing with chopstick turned up a bad joint where I had removed one of the 18K resistors for the C4S install. Thanks for keeping me on task.
Related, I remember the terminal strips I used in the rebuild were difficult to work with, particularly the lower holes. I wiped them with denatured alcohol with some, obviously limited, success.
Thanks again,
Karl