I'm having a problem with my Panasonic AG-1980 VCR. I'm trying to copy a vhs video with it, I'm using it as the recording VCR, and another VCR as the playback one. After about 2 hours, the AG-1980 stops the video, and rewinds itself. The video I'm copying is 6 hrs long. I've tried this twice, and it did it both times.