c.k., I would put all my money on the pressure reducing valve cartridge.This cartridge valve is about midway back on valve stack and has a 3_8' bolt with a jamnut that has been lockwired in place.If hyd. oil has not been serviced regularly a sliver of metal will get caught in valve and when you make a steering manuever you lose the 400psi pressure to keep seperator engaged.(Also valve can stick due to some scoring.Plumb a guage into rear of valve stack to check stand-by pressure(450-500psi.).With throttle at high idle and steering wheel being held against lH stop,guage should drop only 25-50psi..If guage drops to zero,you need to take pressure reducing vavle cartridge out and disassemble.Alot of time you can use crocus cloth to clean parts and reassemble. Good luck and let us know if you need further help, Hyper Harvest II