Intensity Shuttle cutting to black

HI all,

New to the forum and excited about using the Intensity shuttle to archive my clients old footage,
i have setup Intensity shuttle USB 3 to record VHS tapes from a S-VHS player on an iMac , however the input capture keeps cutting from footage to black all the time ? i have changed cables , inputs (composite & svhs)
even tried it on another iMac , it still flicks to black for a few frames constantly, i have a monitor to view the footage separately and it looks stable, any ideas ??

Thanks
Craig

VHS video is not stable enough for a Capture card.. You need to put a TimeBaseCorrector inbetween

Thanks for the TBC tip, i ended up running the footage through my DVD recorder then HDMI out
into the intensity, worked a treat.