Greg,
Those homemade pieces are just that, homemade. Lionel did not use any kind of spring on their 385 trucks. They depended on the weight of the assembly to keep them on the track. You most likely have the wheels 'out of gauge'. When the wheels 'warp', they get spread wider on the axles, and will most definitely ride up on the rails. Try to move the wheels in together so the truck has some side play when sitting on the track. If this fails, replace the wheels. Harry 
