All I can say is for 15 grand, I'd get a second opinion.
Both my M9's exhibit the same thing but only when shuttling under load because the proportioning valve 'senses' the applied load and adjusts the lockup pressure accordingly. Again both mine only exhibit abrupt lockup when loaded heavily. I don't have clutches in the pure sense of the word in my M9's. They have damper plates in the bell housing that reduce imparted shock loads to the the crankshaft, but no 'clutch'. 'Clutching' is done with the hydraulic multi plate wet clutch in the transmission case and the actuation is controlled by an external valve body on the side of the transmission case. why I asked you if it was a hydraulic shuttle or not.
Main reason why I have them. I don't want a dry clutch for ag work because of the lifespan.
You really need a workshop manual so you can determine lockup pressures and pack modulation, both of which are adjustable on my tractors and I'd say for 15 grand, the cost of the WSM is inconsequential.
I could tell you what mine are but I would think yours would be different values than mine and you need a pressure gauge and fittings to access the pressure ports anyway.
