I suggest that you quit throwing parts at it and either diagnose it yourself or pay someone to do it for you. You need a schematic and you need to see if you are getting current to the little wire on the starter solenoid. If you are then it would appear that you have another faulty starter, if not then you need to go upstream and see where the open circuit is, the PNP switch is out of adjustment, the ignition contact plate is faulty? These are just some of the possiblities but you should really get a schematic and diagnose it correctly.

Mark