Volvo FM rear steer hydraulic 2009 issues

I have a Volvo FM 2009 8 legger with rear steer ex milk tanker with a hooklift now installed, Its been to WW Truck and bus to get the rear steer working several times now. Its had pipes changes, new bleed ■■■■■■■ and fluid and recently the valve block rebuilt. Since the rebuild the red light that was always on in the cab sometimes is not and sometimes the lower half goes green. But no where near often enough! Out of 300 miles driven yesterday it came right only for 5 minutes the whole day. Does any one have experience of this earlier hydraulic system that could give tips on getting it functional? Apart from a couple of minor issues she seems a good truck and I just want to get this working.