Ron,
The headline dims (rule 17) but the engine does not move
That's nor Rule 17 lighting. Rule17 has the headlight get brighter when the engine goes forward, not dimmer. Going dimmer is an indication of a power drain.
When the thumb wheel is applied to over 25 SMPH the red light on the Z4000 comes on.
This is another symptom of a power drain. Obviously, there's something electrically wrong, or there's binding that you're just not finding.