First you need to fix the red connector with the broken wire. Look at the connector and you will see a pin where the wire was once attached. You will have to remove the pin, crimp a new pin on to the wire and insert into the location where you removed the old pin. You need a tool to remove the pin or you can use the destructo method to remove the pin.

Then you need to inspect the driver board to CPU cable and check the pins for corrosion and for poor spring. Also all of the connectors can have broken pins or the spring has left the pin.

Read:

http://www.pinwiki.com/wiki/index.php?title=Gottlieb_System_80#Problems_and_Solutions