Quote Originally Posted by InsaneDavid View Post
Try this - put a cartridge in, then pull it back out just a hair. I've had a lot of SMS consoles that have worn connectors, this usually gets them to work.
On a related note, you can also try to pull up the cartridge slightly on just one side (either right or left). I've had to do this with numerous systems for particular games, but it seems to work well.