Thank you for your prompt and helpful reply.
I've tried a couple of power supplies, as well as the USB port on my PC. I get the usual Windows bub-unk chime when plugging the USB, and a port appears in the Arduino IDE Port menu. Selecting that port and resetting the clock produces no output in the serial monitor. The voltage on the two pins you asked about, with the unit plugged into my PC, is 4.95V.
Again, there are no LEDs lit on the board. I checked, and it's actually been 2 years since I bought the board, and since it's been operating properly.
Unless you have another idea, it appears that I need to replace the board. What's the price for the replacement? (I can unsolder the components that were attached with the kit, if they don't come with the replacement board, as you advise. I don't remember what pieces, if any, were soldered on during construction.)
Thanks again!
Dick