Walthers 0-8-0's Shorting

I have two Walthers 0-8-0’s (N scale DC) which I assembled and tried to run this evening. I assembled the tenders to the engines as per the instructions, but when I tried to run them, they both shorted out the track. I tried reversing the plug to the tender with no luck. I have run two Model Power DC locos and a Bachman DCC loco on the track today with no problem. Has anyone had this experience with the Walthers 0-8-0 locos? If so, what is the problem? Thanks, Jim

Check the tender wheel sets to make sure one is not orientated wrong, with the insulated wheels turned around. that would cause a short

Thanks CB&Q, but that’s not the problem. I also have a Walthers 2-8-8-2 with sound that I tried to run after posting the first message. It ran (with sound) for about 2 feet and also shorted the track. It now shorts out when the power button is pushed. Perhaps I need to add more info. I’m using a Digitrax Zephyr and one part of a PSX-3 circuit breaker. I’ve been trying to read over the PSX-3 instructions regarding setting trip currents. The PSX instructions are complete gobble-de-gook to me. The manuals that came with the Walthers engines are completely inadequate. I have returned to the two MPC DC engines and the Bachman DCC engine; and they run fine. I’m lost Jim