Well, it does sound like a dirty head to me and if the clogging is bad tape cleaners often don't work. If you want to try cleaning it by hand - open up and you will see the head assembly, it looks like a spinning cylinder set at a slight angle. The actual heads are two small devices half way down the cylinder, one on each side. Using a piece of soft chamois soaked in isopropyl alcohol wipe the oxide off. It is imporant only to wipe in a horizontal direction to avoid damaging the heads. This is most easily done by holding the cloth still and moving the head unit to scrub the heads clean. They are delicate, but we have been known to resort to a stiff brush in extreme cases. Try not to let the kids play tapes hundreds of times as the oxide soon starts to wear off and clog the heads. Also make sure you put the tapes back in their box to avoid them picking up dirt, and if any thing gets spilt on one throw it away. Tapes are cheap, video heads are not.