Okay, I got this SMS system at a flea market a few weeks ago. I finally got around to playing it and I've discovered that it has something wrong with it. My SMS has Hang-On/Safari Hunt built in. Whenever I put a game in it always starts up the built in game(s). I haven't been able to get any cartridge (or card) games to work in this system, it only plays the built in games. I've tried cleaning both the games and the SMS pins to no avail. What could cause a SMS not to play cartridges?