[laverdur]

The "bucking" while braking sounds like what I had when the wires inside the axle tubes were shorting out after the insulation was worn off. This is challenging to diagnose because the shorting occurs as the wires bounce inside the axle tubes while moving. In my experience, they were never shorted when parked. After hours of troubleshooting and testing I finally cut the wires running inside the axle tubes and ran new wires on the outside. Problem solved.