A WAG, but I think BJNP.EXE needs an update (it should also be included in the package). If I run BJNP.EXE, I get:
[W:\CUPS\LIB\CUPS\BACKEND]bjnp
network bjnp://192.168.0.107:8611 "Canon MP620 series" "Canon MP620 series 192.1
68.0.107" "MFG:Canon;CMD:BJL,BJRaster3,BSCCe,NCCe,PLI;SOJ:TXT01,BJNP2;MDL:MP620
series;CLS:PRINTER;DES:Canon MP620 series;VER:1.040;STA:10;HRI:PAM;MSI:DAT,E3,HF
SF;PDR:B;"
[W:\CUPS\LIB\CUPS\BACKEND]
which seems to be correct.
So, I tried switching to the USB connection. USBdock "sees" the device, but running USB.EXE produces:
[W:\CUPS\LIB\CUPS\BACKEND]usb
DEBUG: Loading USB quirks from "/cups/share/cups/usb".
DEBUG: Loaded 67 quirks.
DEBUG: list_devices
DEBUG: libusb_get_device_list=2
DEBUG: Failed to check whether 04a9:172f has the "usblp" kernel module attached
[W:\CUPS\LIB\CUPS\BACKEND]
which doesn't seem to be right. What does the last line mean?