'E'-units will not cycle by themselves. There has to be an interruption of power.
When traversing the switches slowly, there is a slight interruption of power to cycle the 'E'-unit.

Poor connections between track sections will also cause a loss of power, cycling the loco also.

The slow train speed will cause the loco to cycle, whereas faster speeds get the loco across the problem sections faster, with no cycling of the 'E'-unit.

The newer electronic reverse units may need a slightly longer power interruption before they cycle; hence the run without issue on the same track.


Larry