SN: K061644 with a EV100 panel. An error code 3373 comes up which is not in the Yale manual and is one we have never seen before. The truck jerks hard in reverse and forward as if the truck goes straight to high speed and then shuts down completely. Traction motor light and service indicator light comes on as or after the problem occurs. There is also evidence of arcing in the main panel and at various contactors. Any advise out there.