Transformer quandry

My Lionel Polar Express locomotive runs fine using the Lionel CW-80 transformer, but refuses to run at all when I substitute a MTH Z-1000 transformer. I always thought the Z-1000 would run virtually any locomotive or engine–it works fine with my Williams and RMT diesel engines.

That’s strange. I use an MTH Z-1000 for MTH and Lionels, Williams, K-Lines, and RMTs and have no problems. Weird.

Well, out of the blue PE began running on the Z-1000. I have no idea why it failed before, but I won’t tempt fate by worrying about it.