690ELC Ser#552349. 7000Hrs New pump at 5000Hrs The arm cylinder has a dead spot at mid stroke. The cylinder just stops halfway through its stroke, for about a half second then takes off again at full speed and power. Everything else on the 690 works fine and always has. Only happens when extending cylinder (moving arm closer to machine) retracting cylinder is nice smooth motion as it should be. At half stroke when the cylinder stop and just before it start you can hear a swoosh noise in the valve assembly. Doesnt seem to do it as bad when the machine is cold, or as bad when you run the pump under HD pressure setting. Have noticed after machine has set for a couple of days before you put any pressure to the arm cylinder the arm acts like there is no pressure on one side of it and kinda moves free a foot or two at the bucket. We have inspected the regeneration valve, swapped arm relief valves and swapped machine from deere to cat controls with no success. Almost positive that it is not a problem in the cylinder. Could it be a problem with the spool valve? Also can anybody tell me what the arm cylinder restriction screw does in the back of the regeneration valve?
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