I find the best way to clean vhs heads is to wipe them over using tissue paper and white spirit. This does however require taking it apart. If you cant take it apart i would suggest using a cleaning tape and put white spirit or turps on it before using. play the tape through the machine and leave overnight so the heads can dry. If you put a tape in and its still damp from the white spirit the video tape will get stuck in the machine, so let it dry out completly.
Gary
February 2007