Motorguide issue

So my motorguide went dead on me this weekend at Fork. All batteries tested fine, had a new switch put on the foot control, the blade prop spins great...until it's actually in the water. It dies within a few seconds of use when it's lowered into the water. Anyone have any idea's?

To eliminate any question of whether it's the speed control, switch it to high bypass. If it still dies on you it's likely either worn brushes or leaking shaft seals.

Another possibility is loose or dirty battery cables or defective circuit breaker.