This is something they don't tell you in the manuals! If your TR6 motor is the same as the one in my TR250, then there should be three wires comming from the motor. One goes to +ve - ignition on. To get low speed to work, you have to connect the other TWO wires from the motor to ground (high speed runs if only one wire is connected to ground). As the colour codeing on mine was gone, I had to figure out which wires were which by a bit of trial and error. Now the wiper replacement switches (i.e. not the Hooters original) only ground one feed from the motor at a time, so to get around this, you need to install a power diode between the two switch terminals connecting to the motor. This gives - low speed, both terminals ground, high speed - one terminal ground. Again trial and error to get the diode ponting in the right direction. Make sure your fuses are O.K., and good luck! (Actually I used a low-amperage trickle charger as a 12V source for the "trial-and-error" bit.
Rob.