Have you checked the earth (ground) connection to the solenoid coil?
Power for the solenoid comes through the switch (from the solenoid contact terminal - the same terminal that the battery lead connects to, not the solenoid contact terminal that connects to the starter motor) to operate the solenoid.
As you said that the switch is OK and have replaced the solenoid with a new one then the problem is either the wire to the switch from the solenoid contact, the wire to the solenoid coil from the switch or the earth connection to the solenoid coil.
The earth ground wire was good but when I changed it's position from bottom to top of post...it worked...thanks for the tip!
por Ed Vernon
Does it matter if what side the ground goes on. I have it hook up going from the sol. too starter ,
por Larry Farley