I think the "Y"harness was for a different stick configuration for driving. If you have throttle on a seperate stick maybe? I ran all my tank movement on right stick, so I threw out the "Y" harness and it worked fine. I would maybe try a new or newer battery. You could try unplugging your motors from the Clark just to see if TBS resets. The battery could have good voltage but low amperage. Check wires and connections for good clean connections and solder joints, if any.

Shad