What is the Model? ser #? Electric steer?
G 4 on a 7400 is a steer card fault
G3 is Prox sensor at drive unit. Didnt see it
The prox needs a 020 thou gap. if the steel ring is hitting the prox, the radial rings are gone. look under truck at drive unit, do you see steel on steel wear marks? drive truck with door off, does the drive motor rock back and forth when you plug?
This all indicates worn radial rings. Keep driving it with worn rings and you score a hat trick....steer motor blown, steer card and radial rings