I'm always amused by lights in pinballs...
Ok, I have eight lights out, and they are all connected to the -yellow-green- wire...
(After trying everything possible for an hour tracing the yellow-green wire...)
Nope. All eight bulbs are burnt out.
As part of my standard 'shop' of an Addams Family I pull all the lamp boards and refresh the solder at the connectors. It's so common to find a cracked solder connection causing half the board of lamps to not come on.
I also find myself doing this kind of troubleshooting when I've got lights out on the green boards with the 555 twist-in sockets:
I pull out a non-lighting bulb, I find another bulb that is lighting, I untwist it, and put the (known working) bulb in the suspect lamp hole.
The reason for this is that it is extremely common for the two little fingers on the black sockets to not make good connection to the printed circuit board, and it's extremely common to have the little wires on the bulbs not make perfect connection inside the little black socket. Putting a known good black-socketed 555 into the suspect hole on the board speeds up my troubleshooting.
For most of my Addams Family pinballs, it's actually rare for me to have to do anything with the lamp circuitry. If ALL the lamps are out I've replaced the associated bridge rectifier a bunch of times, but if it's just particular strings of lights being out, I usually solve my problems with replacing an insane number of burnt out bulbs, and re-soldering the connections on every green lamp printed circuit board.
Let us know what you find!