Detent Valve Adjustment

[mtncur]

My M5-111 has a detent valve and a standard float valve. I have the tailgate of my JD 459 baler connected to the detent valve. The detent valve should “lock” when depressed then cancel”return to neutral” when the tailgate opens fully and closes fully. This functions sometimes as long as the tractor is at low RPMs. However, at operating RPMs (540 pto) the detents will not engage, I have to hold the lever. Is there an adjustment to the sensitivity of the detents. I do not see anything in the manual regarding this adjustment and unfortunately my dealer has been less than helpful. Thanks