Noeleberry

Hey all. I have a 1985 12A Automatic Transmission GSL. All original equipment. Sometimes she won't start in park, but will always start in neutral. I say always, but if the blower motor for the air conditioner is on or the radio is on the engine does not want to start. Does anyone have any prior experience with this problem or know possible causes? For the park/neutral situation the FSM says to check in this order: Ignition switch and/or starter motor, range selector linkage, and inhibitor switch and wiring. Tell me if I'm correct, but if the ignition switch or starter were bad the car wouldn't start in neutral. Is it possible it is the range selector or inhibitor switch? WTF is the inhibitor switch and where is it? Are there any contact points in the gear selector that could be dirty or worn? Also, what is draining the starting power?