Okay, the problem is now solved.
Steve, I also tried HDV Split as you suggested, and again got the same issue. The firewire was driving the camera but not seeing any video and not capturing.
So I took it back to the people who did the upgrade and asked them to try my old firewire card, and that worked fine. So, now it is seeing video and capturing properly.
So it looks like the new onboard firewire was dodgy.