The 1664 is a prewar O27 engine. Your idea about tying a tender roller to the engine slider contact sounds very doable. I have two prewar tenders, a 1689W and a much nicer 2666W. I prefer the 2666W because it isn't just a black box. It is O gauge and has two rollers. That would free the 1689W to evolve into an auxiliary water tender to pull behind my LC+ 4501. The 4501 used an auxiliary tender between Birmingham and Chattanooga in the 1970's. That is a young me standing on the primary tender in the attached photo. My Father, an official on the Southern/NS, always ran the 4501 when it was on excursions on the AGS Division. Don't tell anyone, sometimes he gave me the throttle.
The 1664 stalls regardless of E unit position.
Bill H.
