VHS to digital converting problems?

I am in the process of digitizing Veterinary Ultrasound scans that were deemed interesting and saved for later examples of what different conditions look like.

They were recorded on Sony 6hr tapes, but I am not sure of the setting.

I originally tried to connect my Sony VCR to a Dazzle DV Bridge straight into my computer, but iMovie, which I am using to add some titles and organization to the scans, said it cannot accept the input because it is sending half-frames.

I then used my Canon Elura 60 instead of the computer, playing the VCR and recording that output onto the camera. At first, it worked and I showed one of the techs what I could do, editing and all. I got the go ahead, and tried to convert more. However now, the camera will stop recording and say that it cannot record, as dubbing is restricted. First it was intermittent, now it is whenever I try to record.

I am trying other set-ups, but so far no avail. I do not have another video editor. I am using a 1.83 Ghz Intel iMac.