I can’t find a wiring diagram, but it is a simple setup. You should have a three post solenoid, two large terminals and one small one. One large terminal should have the battery + cable coming to it. Othe large terminal should have a battery cable connected to it going to the starter. Small terminal should have a small gauge wire attached, coming from the key switch. Large terminal, to which the battery is attached, should have a small gauge wire which goes to the key switch. Hopefully you did not switch the two small wires. The one attached To the battery terminal should go to the B terminal on the key switch. The other small wire should be attached to the S terminal on the key switch. If everything is attached where it should be, I would agree, time to check the key switch.