Did you check the radial bearing?

ok so not so old as i thought

must be some input sensor problem i guess

`When driving truck steering it out.
The turn plate has been rebuild
The power steering motor is new with gear box
Steer encoder has been replace
It does not have any codes `

OK...i`m assuming the `turn plate`is the drive unit?
You have a new steer motor kit complete? steer encoder is inside the steer motor. Did you replace the steer prox?
Tell me, when you lose steering, is there any noise from the steer motor at all? does it try to turn the drive unit or is it just silent?

If there is no noise, no codes, the steer tiller may be bad. is there play side to side in the steering wheel...but more common is the steer card. it`s located on the firewall near the EPO red button. It may not see the tiller commands and wont power the steer motor. it can fail if you had bad radial rings and the drive unit seized up, burning out the steer motor, overheating the steer card. If you dont have another truck to swap parts to test, tap on tiller when the failure occurs. wiggle the wires at the steer card. can you access superword and see the inputs from the tiller on the display?

The power steering is electric

there a pressure transducer on the steering pump?
also could be a timer issue or input issue from the foot pedal switches?

just a wild guess ;o)