To put the same thing a little differently;
On the 4-terminal reversing switch, it doesn't matter which wire is attached to which terminal AS LONG AS:
1) the two wires from the brushes are attached to two terminals which are opposite each other, not adjacent to each other; and
2) the wires from the power pickup and the field winding go to the other two terminals, which are also opposite each other, not adjacent.
If you are having trouble seeing and tracing the wires, a simple step after taking the shell off the frame, would be to take the motor out of the frame. Usually this is just 4 screws in the motor side plates, and the motor will drop out of the frame. Then you will be able to see into the ends of the motor more easily; also easier to work if you are going to slip some insulation over that pickup wire as Ron suggests. Not necessary to do this, but sometimes easier in the long run.
