As I mentioned in #19, measure the resistance of all the motor conductors, WRT each other.
Final Polarity will depend on the direction required.
Max.

 

This is how to wire it up.

Some variacs have an extra tap so that they can boost the voltage above the input voltage. If your's has this tap then wire it so it's ouput only goes as high as the input voltage.

Les.

 

To change direction, swap either armature or field polarity.
Don't forget earth conductor to motor frame.
Max.