I just completed another Robert Ray’s kit, Opera Window Centerbeam car’s in the Western Pacific livery scheme. Everything went well on building the kits, until I tried running them on the layout, and they kept derailing of the track around the curves. Tried a few things to fix the problem to no avail. Then it came to me why not take the trucks off, and sand off the paint on the bolsters. It was the paint making the trucks not turn correctly. Once trucks were back on they all worked like champs! Happy to add some new cars to my layout!