Congrats!
Looks like that player one display is on the fritz, and the other 3 are dim. If the game is otherwise working properly, it can't hurt to unplug the connectors from the displays and using a pink rubber eraser, clean off the male card edge sides. Make sure you do it with the game off, and be careful with the small glass "nipple" on the back of the board! One chip, and the display is a goner. You can brighten up the other displays using a method that burns off the corrosion inside of the glass, but I don't like to do that unless they're super ultra bad and dim. If you want to go ahead and do that though, the procedure is documented here:
http://www.pinwiki.com/wiki/index.php?title=Gottlieb_System_1#Rejuvenating_Tired_Displays