The problem isn't a short.
You have an open somewhere in the circuit.
Study this. Get out your DMM. Everything you need to know to fix this is in this article.
Let us know what you find.m
BTW...the lack of coin door illumination means that the proble is with the purple/white-purple wire circuit.
Chris Hibler - CARGPB #31
http://www.PinWiki.com - The new place for pinball repair info