Graham,
Sorry to hear you are having the same problem I did. How I eventually solved the issue was to connect my FW400 cable out of the deck into a small, portable Lacie 160G drive, and then went FW800 out of the drive into the iMAC. So the drive acts like a router/converter. I don’t use it for anything else, but ever since I tried it, it has worked perfectly. The original problem seems to be on Sony’s end, but since the deck is EOL, they didn’t seem predisposed to come up with a software fix.
Hope this helps.
Rob
“If you’re walking on thin ice, you might as well dance”