The 40 fault wasn't an issue with the back to backs, it was the pony wheel which had so much movement that it derailed the bogie, we sussed it out on a layout one afternoon. The fix was a doddle 4 pieces of plastic tube sleeved over the pony axles, easy to do but took longer to suss out why it was doing it. I agree more pics but would say this one is a winner. What next a Class 56? I've heard rumours!