9F The Original Circuit Board

Viewed from the right hand side, the circuit board is secured to a metal post above the worm gear.  The two strips of phosphor-bronze contact strip extend the pickups from the right and left front 3 axles.  De-soldering the strips is easy - as soon as the solder melts, the strip will spring away (or up) from the circuit board.

Re-soldering it is a bit more awkward. You need one hand for the soldering iron, one for the solder, and another to hold the screwdriver which holds the vertical copper strip in its place until the solder cools. Don't let go before the solder has set properly, or you will get a dry joint which will not conduct electricity properly.

The circuit board is simple and contains only a choke coil and a capcaitor which hep to eliminate the high frequency radio interference that comes with running electric motors near radios and TVs.  The green wires is the lead that connects to the lower motor contact.