Did you break in the gearboxes Bill with gritty hand cleaner or toothpaste? Wire the motors to run directly off a battery outside the tank, put some paper over them to contain the mess and do something else while listening for slow downs. When the gearbox encounters resistance, add more toothpaste, and more and more until about an hour has past. I also run them backwards for about 30 minutes too. Still, even with that and after taking readings on my watts up meter they still sometimes act up. I liberally coat them and the bearings after cleaning with white lithium grease and run them in making sure there aren't any squeeky spots, then fasten the grease splash covers.

Murphy is in China right now trying to get the quality issues with the gears resolved.