Pert, thank you for your thoughtful response. I replaced the USBasp driver per your clear steps with Zadig.
USBasp now shows up in Device Manager under libusbK Devices, but still doesn't seem to be talking to AVRdude in the Arduino IDE.
AvrDude still reports:
avrdude: error: program enable: target doesn't answer. 1
avrdude: initialization failed, rc=-1
Any suggestions welcomed. Many thanks again for you time and expertise, Pert.
Bruce