A while back, I’m not sure if it was here or on the Bachman site, a fellow suggested that the Hogwarts was a decent train if you added weight to the front of the locomotive and to the tender. I can see what he means. The front truck seems to float and the slightest irrgularity and it spins.
Now the tender is easy. I added a .38 cal bullet and it rides a logt better. But adding weight to the engine leaves me confused. I know I can open the loco and put weight above the front truck, but don’t need the weight on the truck?
The pressure on the front truck is caused by the compression of the spring pushing down on it. Adding weight to the engine above the truck (and above the spring) will increase the weight on the front driving wheels of the engine itself since the frame is rigid. This increased weight will enable the engine to pull more cars. If the front truck still bounces off the track, then that spring should be stretched or replaced with a stiffer spring.
Steamers are notorious for needing to be balanced in regard to weight. Diesels with trucks at the end and able to pivot are more forgiving. With steam engine drivers rigid to the boiler wieght transfer significantly affects tracking ability. Most steamers have the motor at the cab end and naturally are tipped in that direction. the higher priced steam engines will add weight to the front to comensate.
Spacemouse:
In case you are not aware of this, prototype steam engines actually support part of their weight on both the pilots and the trailing trucks. You might get satisfactory results by simply adding a metal washer or other weight directly to the top of truck if a spring is not practical.