well, which one do you have? they 2 are completely different systems, made by 2 different companies. one is by "Taito" and the other by "ICE"
a simple segment not working could either be a bad solder joint or a bad LED inside the SSD itself.
your first step would be to verify the segment and/orother lamps that aren't working, are in indeed, getting power when it should be lit up. if it isn't you may have a control logic issue.