Per friends at Amtrak and Bombardier, the biggest maintenance issue with private cars these days is wheelsets. Many of the cars have different size journals; brake components vary as well. Amtrak is closing out their Heritage Fleet operations, which may free up some components. Then again, Amtrak may already have run out of some truck and wheel components. I have been told that if AMTK car # 10030, the Big Dome, ever suffers a major truck issue, it will have to be parked as components for these trucks are non - existant nowadays.