You remove the lug from the output gear that would otherwise foult the ribs inside the top cover, then you enlarge the "D" shaped hole in the bottom of the gear so that it does not engage the position sensing pot. Adjusting the pot also gives some measure of speed control if it is running off an RX channel. Otherwise just remove the electronics board and connect the motor terminals to a battery, voltage of your choice, but I would say a max of 6v.