Help! - Problems with copying VHS

[Dan P]

I have a Marvel G450 and am experiencing problems making copies of videos through VHS only. Basically these are copies of games and other sports events that I had recorded off cable (digital) onto VHS (SP). When I try to copy certain tapes, they will play back very choppy. This happens regardless of the bitrate or size. When I capture directly from cable, there are no problems at all. Is this a problem with the signal on the tape?