Komatsu FB20H 1R

Hello.

Hydraulics wouldn't function unless brake pedal pressed.
Display shows Lift Lever or Setting when powered up meaning there is a calibration issue on hall sensor.
Following the manual to calibrate it wouldn't go to Lift Set, suspected the hall sensor and changed it for new one. It calibrated up ok and worked first time I tried it. Then operator got on truck and hydraulics began to stick on. Switched truck on and off and display back to showing Lift Lever and hydraulics inop.
You can apparently reset the calibration by holding 2 buttons but nothing seems to happen.
Really annoying as it worked first time. Could this be an issue with the hall acting sensor power card?