MV-JR Y axis OC error during rapid Z plunge only

When plunging at rapid, the machine will alarm with an OC (Over current) on the Y axis. (Yes, Y-axis) It only happens at 100% rapid. And it is ALWAYS an over current on the Y-axis. Sometimes it very randomly happens when the machine is sitting idle. But is fairly repeatable when plunging. It nearly always happens at the bottom of the plunge, where the tool is just above the part. (a inertia thing?) Have talked to others and Mori Service.

According to others, the problem is dirty commutators on the motors. (more resistance = more current) And a bad regen/braking resistor. Each servo has one. I swapped X & Y servos, and I believe (IIRC) the problem moved to the x-axis motor, which points to the servo. But I need to attempt that again to verify.

Mori suggested coolant in the wiring harness to the Y-axis motor. Or a wire chafing in the harness. I checked for that and could not find a break anywhere. Nor could I force the error by moving the cables around. If the error moves when swapping drives, then it cannot be the cable.

Suggestions/solutions? besides replacing all the drives and motors.

ca