Faller Playtrain diesel locomotive

The German company Faller produced a range of attractive narrow gauge locomotives and rolling stock in the 1980s under the Playtrain brand. The locomotives were available with either 12V motors powered via the track, or 3V battery powered motors. I found a mint condition 3V diesel shunter on eBay, and decided to convert this to simple radio control.
The Faller locomotive is very basic, with a clip-on, well detailed, moulded body. All the parts, including the wheels, are made of plastic. The single driven pair of wheels are fitted with rubber tyres. It might not be very authentic, but it certainly helps with adhesion. I suspect however that I may fit metal wheels in the future.
The locomotive was designed to take two "C" cells. I replaced the battery area with a lead weight, and decided to to use smaller "AA" cells as these could be dropped in through the removable roof. The 40MHz remote control system is a very simple and cheap Chinese model with the brand name "New Bright", probably designed for a toy car. I used a single channel to provide forward-off-reverse control. I did not bother with proportional speed control since this would have been more expensive and really isn't necessary on this small locomotive.
The small transmitter also takes a pair of "AA" cells. Range is a little limited at around 10 feet, so it is necessary to stroll along with the locomotive. Since the main users of the locomotive will be children this should not be a problem.