I have a Hogwarts express , 1 Hogwarts Castle (nee manor) and two passenger cars. It very hard to keep the tender and the passenger car on the track.
 
1) Is the 18 inch curve too tight? is 22" needed?
2) Should the passenger cars be weighted more, they seem very light and seem to be pulled off the rails on curves
This is unit of several years ago but is basically in new shape.
R Goddard