What the diagram says is if you activate the switch to UP, then 12V is applied to RED and GREEN is connected to grou nd by the other side of the switch.
if you activate the DOWN switch , then 12V is applied to GREEN and RED is connected to ground by the other side of the switch.
So disconnect the motor and then you can use an ohmmeter to test the motor itself. Best would be to run 12V and GROUND to RED and GREEN motor wires, and reverse, to see if motor operates.