Code 127 Hyster Gray box liftcontrol (GE) controller

I drive and lifting and tilting etc shift for half hour no problem and than I do shift al hydraulics stop

Only steering works and drive
I do reset with key start up Again everything works perfect 1 hour no problem 2 hours no problem shift all stops end sometime's he work again problem one second.
I go crasy I did measerments on box pin 1 and 2 are 80Volts print for the levers 80 volts out put of print to Box oké wiring is all good
Wiring 51-52-53 all oke I did test outputs to controller they oké 4.7V neutral and make move the lever its up to 9V When all works same measerments
I think box is not good
somebody have any Idééé

Regards
John.