We have a 2015 T590 put the grapple bucket on it today and when i activate the aux controls it seemed to cause a bad vibration for a minute and then when i would use the foot pedal to raise or lower the arms the grapple would open on its own. I could close it using the thumb controls but it would open again on its own. then it would stop and work fine for a bit but then would start doing it again. like somehow the foot controls are bypassing in control valve to the aux. I havent run across this situation before anybody have any ideas?
One if your aux stems is sticking, or possibly a broken centering spring on the aux spool
thanks thats where ill start