I have seen a similar issue before on a TMG15 where the drive would hesitate when turning, and it turned out to be a worn steering angle sensor causing the controller to lose signal briefly in that range. It might be worth checking the sensor alignment and the wiring harness around the steer motor for any loose or corroded connections. Sometimes even a small break in the wire insulation can cause intermittent loss of power to one wheel. I also came across a helpful reference on a case study about signal drop under load that pointed to the same kind of fault. Has the dead spot been there since you got the truck, or did it start happening gradually?