Thank you, thank you, thank you, to both dugprat and especially to PAHU.
Canon's 10.8 driver did not work on my machine (iMac with Yosemite 10.10.2). After installing that driver (and rebooting / restarting everything), the print que window very, very, slowly pops up in the Dock and (eventually) states that it is ready to print. After several minutes of inaction, it fails. I installed two versions of the printer (one direct USB, one installed on Time Machine), each have the exact same results.
I installed Gutenprint (right-click to install) and, literally, instantly the print que gates opened wide. . . . Ok, so I now have a small pile of paper to be recycled.
The read-me text file for the Gutenprint says it does not support scanning or other functions other than printing. Once it was installed, however, I was able to use Canon's MP Navigator (which did not work with the Canon 10.8 driver). Scanning works like a charm.
One more tip, I use a A/B switch to connect the iMac via a USB cable. This is the only way I have been able to scan (Navigator does not see network printers). Most of the time I simply keep the network side (Time Machine) on. When I need to print, it is a simple switch.
Thanks again.