Some general info on our hydraulic systems.. When depressuring the system with the bypass valve, open the valve quickly to keep the hydraulic fluid from "wire-drawing" or cutting out the seats, which first starts as a very small weep or a blurp of the pump in the air. Secondly, it's necessary to have the reservoir dip stick not down too tight or the have a vertical slit across the threads to relieve air surges.  Regards to all.. Don Skeele N320J