"Bill, isn't your wiring diagram missing some wires to terminal 1 and 4?
I don't see how throwing the switch would reverse a motor."
The motor wires connect to both the 3-6 pair and the 1-4 pair, but with reversed polarity on the 1-4 pair.? This of course only works on DC motors that reverse with reversed polarity.
Note that it would work the same if the motor were connected to the 2-5 pair and the battery to the 3-6 and 1-4 pairs.