OK, so, think this through. You are NOT getting 120v at the switcher. But you ARE getting 120v where the power cord enters the game. That means that somewhere, between where the power cord enters the game, and the power supply, there is a break. We can't do this for you. You are going to have to follow the wires. Something is wrong. Either a broken wire, a blown fuse, bad fuse holder, interlock switch... something. There isn't much in this circuit. I think you need to go back and check. Carefully. Use your meter, don't just eyeball it. Fuses can look good, but be bad. Connections can appear solid, but the wire can be broken inside somewhere.
-Ian