The Turbo Grafx 16 is one of the most collectable video game systems available today. Rather than using the standard cartridge, the Turbo Grafx uses hucards. These flat credit-card size games have contact points at the end which is inserted into the system. Over time the contacts on the hucard can become dirty resulting in the game being unplayable. A great method for cleaning the contact points on the hucard is rubbing them with a polymer eraser. The difference between a polymer eraser  and a standard pink eraser is the polymer eraser doesn't leave any residue after you rub the contacts. Often, pink rubber erasers can smear making the situation worse.  Polymer erasers are readily available and affordable too. I purchased a 3-pack from Pentel at Target for $6. They are white in color and the side label reads hi-polymer eraser. Sometimes it takes more than one try - don't give up!