Larry, locking the e-unit is not a "fix" for this problem as the e-unit was/is a design function for these trains. If there was an "interruption of power" it would not elect what vintage the engine was to interrupt yet we both have this issue with the vintage engines, not, in my case, with the more modern engines even thought they have the same pickups as the older version. Yes, I bandage the problem by doing what you suggest but again, it is a bandage that does not allow use of the full features the engine offers. I've had this happen when using my whistle at times too on these older engines. It almost seems like something happens to the current at some of these track junctions or use of electrical functions which fakes the early (or perhaps more worn) e unit into thinking there was a power interruption.