I just received three MTL "well cars" for my modern AZL North American train. They look great and the containers I got fit perfectly but they will not stay on my Rokuhan track. They do not like going through the turnouts even straight through. One is a little better than the others, I noticed it has very free turning trucks, but the other two have stiffer trucks and I can't use them at all. Reading the instructions on the packaging the couplers appear to be the correct height and I am not using the MTL magnetic uncoupling feature, so I don't think that is the problem. But the wheels just randomly jump off the track in turns (220R) or at turnout track imperfections. The couplers appear to have some "springiness" fwd and aft but that appears to be designed into the couplers. This is my first experience with MTL. And I can't use them... Any advice? I'll add that the InterMountain and Full Throttle cars I got have no compatibility issues and run well. The internal weights appear to be loose in a couple of the InterMountain cars but they don't seem to be affected on the track.