Lets not condemn the circuit board yet!
terminal 1 is main power to the solenoid from the battery. Diagram MP85-2015 says it should have a fuse.
Drawing MP85.2025 indicates that the relay is energized by the blue wire 9000. You should have 12 volts DC coming out on wire 9000. I beleive you do if your "dash" park brake lights up if equipped. Don't be confused as it has two sources. You should have continuity between red wire 6120 and blue 9000.
Did you clean the contacts on the switch plate and the contact ring? Can't remember whether you said you did.