[woodcote]

   

That's what is inside the WRC car. There is a small capacitor on the motor. It looked like one of the legs might have been shorting on the motor can, but removing it didn't make a difference. I also looked closely for any dodgy soldering on the PCB, but it looked okay-ish - and everything (car + lights) was working on the Go!!! powerbase, just not GO Plus.

When I removed the PCB and joined the wires direct from pick-ups to motor, the good news is that the car now works with GO Plus - and counts laps. The bad news is no headlights. And it's also a bit slow now - but that's almost certainly something I did and can be rectified...