Al - Could it really be the Circuit Breaker's resetting that quickly? I count at least 10 resets a second (approximately). According to the Snap Action specifications
http://www.snapaction.net/pdf/MX5%20Spec%20Sheet.pdf
this reset time equates to roughly 500% overload on the Circuit Breaker, which would be 200 Amps. I acknowledge that my times/percentages may be off, but wouldn't the 120A CB be resetting as well? And if the motors work sometimes, (assuming they are using it with a PWM Y-Cable) doesn't this make this argument valid as it does work sometimes (at low rates of acceleration)?