Quoted from Bos98:So I think I figured out what may be killing at least one set of transistors.
This should be 50.2 Ohms resistance and mine measures 0.0
http://www.marcospecialties.com/pinball-parts/090-5031-00
$30 + Shipping ouch.
Still no idea why the GI wont work unless the coin door is opened unless this being on the same harness and being faulty is the cause.
Are you measuring it the right way? Keep in mind if you are doing it wrong it will appear shorted because of the diode.