Sticky 3rd function valve

[pdcl]

I have a WR Long 3rd function valve on my MX5100 for using a grapple. When closing the grapple, it regularly sticks when I let go of the switch. When the switch is disengaged, the hydraulics are still trying to close the grapple. I can tell by the sound of the machine when it sticks. It's like I'm still holding the switch when I'm not.

I don't think it is the actual switch on the handle. It sounds like a hydraulic valve is stuck open. To disengage it, I have to press the switch to open the grapple a little (usually not what I want to given what is in the grapple), or continuously try to close it over and over until it eventually unsticks. The valve only sticks when the grapple is all the way closed and there is a load on the actuators. It never sticks when I'm closing the grapple and let go of the switch before the grapple actually clamps down on something.

I had a dealer install the kit when I bought the tractor, so I didn't get any instructions. It's about 9 months old, but I've never used it prior to this month. Does something need to be adjusted? Should I only be running this type of electric valve when the RPMs are high (I notice it sticks less often when I am running higher RPMs).

Any help would be appreciated.