Response from Jonathan: David,

You might try using a multimeter to test to see if the joystick down wire is connected properly to the harness. You can do this by setting your multimeter to continuity (or diode) test and placing one probe on the joystick down pin on your harness (looks like pin 14 on the solder side according to the pinouts below) and the other probe where the joystick down wire is connected to your joystick.

Pinouts for Ms. Pac Man: http://www.mikesarcade.com/cgi-bin/spies.cgi?action=url&type=pinout&page=Pac.html

If you do not get a good continuity signal, you probably have either a bad harness pin or a break in your wire somewhere. You can test the leaf contacts on your joystick using this method as well. Also, make sure the game is off as you don’t need it powered on to check the continuity.

Hope that helps. Thank you for your question and good luck with your repair.