I have two sets with extra cars. The first Amtrak set had a close coupling problem with the power cars. Mike Wolf and I worked out a fix that was perfect. I run the wheels off my set and have never had wire issues. I did add the correct red LED to the end car. I put my sets on the rails and leave them. I have had no other issue. I rode the Turbo Train back in the day and was always a fan. I have been inside a few and they are easy to work on. I am reading about guys with wiring issues and I have not seen that with my sets. I do agree about the way they plug in. I am also not a fan of that. I might have saved the coupling post somewhere if people need it.
I have never had to look at wiring. My area has many people that purchased the Turbo train as it ran through our towns here.