This is for those who are thinking about or have just bought a Spectrum Class J. Some would tell you that they have bad mechanisms. As long as you don’t “abuse” it by making it pull heavy trains, you’ll be okey dokey.
Really what I’m tryin’ to say is, if you have one of the newer Spectrum models and it rolls over a hump in the tracks, the tender attatchment may cause the tender’s front to lift off the track and derail. Try loosening the bracket/attatchment cover on the tender a little bit (and I mean a LITTLE bit). Keep it tight enough so it won’t fall off. I tested mine on a piece of flexy-track with a small hump in the middle (with some “supports”), and it works.
If this doesn’t help (if anyone has faced this dilemma), my apologies, and I have and alternate method that may help.