Kobelco SK200-V hydraulic Issue

Hi All
I've had a Kobelco SK-200 Mark5 Super for a number of years. Great machine with almost no probs. Recently did up a traxcavator 4:1 bucket and plumbed into auxiliary hydraulics that used to run a tilt bucket. Got it all running OK but since then the hydraulics are funny. At idle I can hear the pressure relief valve functioning. If I action something the relief valve whine stops and the machine functions OK. If I give any throttle and don't action anything the machine stalls, but...

Kobelco SK200-V hydraulic Issue

Kobelco SK200-V hydraulic Issue