Quoted from rufessor:

Yep- I use a cutting disc too and remove all the wires- makes it easier to see the switches
Butt seriously...
If you want to get this to work, your going to need these things in the following order-
#1 Schematic
#2 Schematic
#3 Schematic
#4 A few basic tools
#5 A willingness to be wrong a lot and slowly start to figure stuff out.
First advice you received was good- EM machines work very very very modularly- so if you pick a simple problem you will most likely find a single maladjusted switch causing it. This is amazing really- the issue is finding the switch among the hundreds under there- thats where the schematic comes in.
There are a bunch of guides to reading a schematic- read them a bunch of times and always remember a schematic is NOT a wiring diagram (not even close- not even remotely close) but it IS a connection diagram and you can follow the path of the electricity to and from any switch and see what other switches it goes through- this is how you fix games. You identify a component thats not working, then you start at the physical thing and check it mechanically and then start tracing back or up the chain for the electrical connections required for it to work.
Pinside is amazing and there are SOOOO many people here who will help you. Let us know if you have the schematic, and then you can start to learn how to find switches and coils!! Trust me, this is FUN!