Locate the bottom of the esc. On the bottom of the esc there are four 2mm cap head screws. Remove the screws to get to the inside of the esc.

While you are in the esc on the top of the circuit board is DC, but because the ESC is oscillating the current in a frequency across the three wires, it has similarities to an AC current, when controlling the motor.

Now spray the bottom of the esc and the bottom cover with simple green. Then brush off the dirt and rinse with water go get off the excess simple green.

Finally replace and screw back the bottom cover of the esc.