Two ways to check the switch. 1) You can apply 12V with a test lead to the terminal that you believe is the "hot" input. Then with the black lead of your meter grounded check each of other switch terminals with your red lead and see if any have voltage with the switch "OFF". Then turn your switch to each of the "ON" positions, and again check each of the switch terminals with your red lead, making a diagram of what you find. 2) With your meter in the "Continuity" (Resistance) position, put one lead on the terminal that you believe to be the "hot" input, and then look for continuity (electrical path) on each of the other terminals with the switch "OFF", and then in each "ON" position, again making a diagram of which terminals are "HOT" in each switch position. A little analysis of the outcome should point you to the right terminals for the motor to work right.