I just finished restoring a Gottlieb Volley for my fathers 60th http://aussiepinball.com/index.php?topic=6311.0
EMs took a little while for me to get my head around but if you have the schematic, everything is in front of you nothing hidden in ICs etc.  I was still very glad that nearly everything was working for me as a lot of the colours on wires fade over the years making the fault finding just that little more difficult.  Good luck, there are heaps of guys here with extensive EM skills who should be able to help you out, as they did for me.