I have an NBA on NBC Arcade game that I am trying to restore.  I have everything in working order but my 3rd player joystick does not work properly.  When I press "down" is goes up.  Any ideas?  I have checked the wiring and everything seems okay. When I enter the test screen of the game I notice that the malfunctioning joystick registers different numbers than the other three working joysticks. Any help would be appreciated.