Some interesting replies there.
The Berkshire tender has rollers on both trucks, for its (presently disconnected) air whistle and bell. The MPC Hudson has sockets for rollers. This all sounds as though it is turning into part of the “Hudson air whistle” conversion project.
The Berkshire has wipers on the trailing truck. I thought these related to the smoke and reverser on/off switches on the footplate, but I think it is just an additional earth (ground) contact. I’ll reconnect the wire (currently detached).
The locos do, indeed, display momentary arcing underneath when passing over switches, particularly when running over the curved side. There is also one particular UCS which the Hudson doesn’t seem to like. I’m making some changes to the track layout so that (a) the larger locos don’t pass over the curved side of the switches (b) there are no UCS adjacent to switches, and I’ll see how that works out.
