From piniwiki:
Williams missed a couple of tricks in and otherwise good design. They are:
No fuses on the 'AC side' of the Bridge Rectifiers. This can be fixed fairly easily and needs to be fully documented with pictures.
Basically you add an 8A fuse and fuse holder to one side of the AC input. Do this for both the BR's. As it's AC voltage, it doesn't matter which wire of the two you fuse, find two the same color and fuse one of them. So for example, put a fuse in-line to one Red and one Blue wire. Easy to do and it may prevent a fire.
Yes I can test switches individual its not the button, it may be the coil switch itself or something on the board that controls the power to that flipper is shorted. I did find the diode on that coil was broke but I replaced it and its still stuck so Im looking on pinside for what I should be looking for to test.