I have a 9n with a due all loader. It has a gresen 12 gallon a minute pump. The spool squeals like crazy and almost kills the engine when going down Had the cylinders and spool gone through. Next step is to put a different ring in the pump to cut it down to 3 gallons a minute. I think it would be to slow. Backed off the pressure valve on the spool so it almost works like it should. Any input?