Fitted the chip which was a doddle as there is plenty of room, removed the caps, tested and after running a couple of feet, l was unable to change speed of loco, it stuck at original set speed. Tried in reverse with same result. In one instance, it even changed direction on it's own! I tried other locos, all worked fine. I then disabled analogue DC in CV29, still no change. After much head scratching, I thought that spikes must have been corrupting the DCC signal. I decided to refit suppression caps to loco, tested, ran like a dream. This definitely goes against the well-tested "remove capacitor" logic, but I'm happy
Has anyone had experience of runaway locos? Comments very welcome.