Returning to this thread, our chuffs on the Lionel TMCC Y6B completely disappeared. But we can now see that wires have come off of a location above the second front drive wheel (see photo - white surface with 3 posts). There is solder residue on the front 2 posts and back one is clean.
Does anyone know if this is in fact the chuff sensor, and if so, should the wires be attached to the front 2 posts.
Thank you!