Well, I found an interesting workaround that didn’t occur to me until I read an article in PC World.
Despite finally managing to make contact with Pinnacle support, the card still hangs upon capture. I had started to look at buying a new capture device – there’s a few USB2 devices knocking around for £40-£80. I came within a gnats knacker of ordering one, but noticed a throwaway comment in a PCW magazine about using a camcorder as an Analog to Digital converter.
Bloody genius! What I did was to hook the analog inputs of my Canon MV5i-MC camcorder to the output of my VCR – just needed £10 SCART->composite converter from Maplin. Then I connected my camcorder as usual via Firewire to my PC, change a setting on the camcorder to put it into A/Dl converter mode, and hey presto! Press Play on the VCR, and get I clean capture of VHS video on my PC.