Model Railway Forum

Can say without seeing the loco! A few close up and clear pictures of both sides wheel motion rods may help?

I hope these help. The only thing I can add is that the short can be intermittent; when initially placing the loco on live track to photograph there was no short, yet with a bit of a wiggle of the engine the short occurs.

Carl, are you able to remove the decoder and replace with a blanking plug and test on DC to see if the problem goes away?
On DC, you may see a small spark if the motion shorts any of the wheels.
Any stray solder or bent pins on the decoder socket?

whats this, circled in the image?



That looks like it could be touching the motion on both sides...

Sand pipes.

Process of elimination ....
What happens if the loco runs without its tender. Does it still short occasionally?
Can any of the driving wheels touch the metal chassis - side to side movement? So as for example, front driver touches left side while rear drive touches right side of the chassis?
The idea of running on DC is good, as in a darkened room you should be able to spot any spark occurring and make an informed opinion of what is causing the short, which you probably won't see on DCC as the DCC power will shut down to fast. If you can run on DC ensure the DCC controller is disconnected from the rails.

Thank you for the advice, testing will be undertaken.