We have tilt and 4th hydraulic function, but no lift or side shift.

I have fit new levers but no success, do these need programming or setting up? The potentiometer can only be in a fixed position.

While messing around with the levers I found that the lift sometimes worked after lightly touching the tilt although not every time, is this a red herring? I also thought I detected the sound of hydraulic flow, again not all the time, when the levers were not being touched. But because of noisy environment I cannot guarantee. This truck is in a chicken slaughterhouse so not the best place for a more electronic sophisticated/complicated (unnecessarily) machine.