You most likely cannot! that is unless its happening only on playback, this being verified as having recorded OK by using some other Mini DV camcorder to play the tape back in, this does not necessarily require the playback to be in the same make / model of device so long as its mini DV. If the aforementioned "is" verified as applying then the camcorders video head requires cleaning, but if the problem shows up when the playback is tested in another camcorder then I am afraid this has happened during the recording and you cannot do anything about it, with a very likely reason for the cause of the problem being a bad tape.