3 years ago I found an excellent WCS for my friend's 1st pinball game that was dirtier than yours and it cleaned up perfectly. It also had the original batteries from the factory and my buddy couldn't believe they never leaked. All I had to do it shop it out, have one of the GI connectors replaced and reflowed new connector to board ,.....Perfect.
Enjoy the game it's a lot of fun....well you should know you already have one!