An earlier version of this post disappeared into the aether instead of posting. Apologies if it turns up in the future. Sometimes posts get lost it appears.
Anyway, while investigating a dead short in my DCC layout powered by ESU Cab Control I also tested the newly installed decoder in my old series Russian Decapod (no sound but DCC ready. ) It also dead shorted the layout. Oh oh. I used the TCS KAM4P SH (short harness) which is idiot proof if you follow the TCS installation instructions. I’m clearly not an idiot because I managed to screw it up anyway.
I took the trucks off, not necessary I now realize. TCS installation page is accurate, the tender retaining screw can be removed by turning the front truck just so. Turns out it isn’t enough to make sure the tender trucks are installed opposite way round tom each other (duh) they also have to be correct front and rear. I just had to swivel each truck 180 degrees and retighten. Tender power pickups are of course polarity specific front and rear.