Sounds like the camcorder needs repair. These ports can be "blown" so off to the repair shop.
I have a Canon Optura 40 and an Intel iMac. When connected by firewire, the computer does not see the camcorder, though the camcorder does say "DV In." Same problem connecting to 2 other Macs. I've changed firewire cables but it's no different. Other firewire devices work. Canon says it's not a Canon problem because of the "DV In." This used to work.