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There are several things that can cause this to occur. If it were me, I would first jack the front wheels just off of the ground. At this point there is no resistance to feedback to the spring-loaded actuator sleeve, and it should turn smoothly from extreme left to right. If it feels like it is catching or hanging up any place in the rotation, I would dudpect something dragging in the rotary cylinder in the pedestal. Not necessarily so, but it can. Next is the bobbin valve. When you turn the wheel, if the torque required is greater than the spring-loaded cam to actuator sleeve can stand, the cam turns and the sleeve stays put, just for a short lag. Now the cam, riding on the two 1/4" dowel pins, moves the sleeve fore or aft depending on the direction of the turn. The sleeve is linked to the bobbin valve and as the sleeve moves fore and aft, the bobbin valve does the same, which directs oil to one side or the other of the power steering pedestal. If the bobbin valve has a burr on it and sticks in theither direction, the oil keeps flowing and you can't turn it back. I would check this valve for burrs, chaffing, or gauling. Next is wear on the two little pins and the cam and the actuator sleeve face. The cam and the sleeve have a form ground in them that is parallel, and is made so that a 1/4" dowel pin fits just inside the slot. If the faces are smooth and the pins have no flats on them, it moves very easily. Most by now have flats worn on the pins and a depression in the cams faces right where the straight ahead position is. You can replace these parts ($$$!) or if you are good with a die grinder, reform and blend them, using a 1/4" dowel pin as a guide until they are parallel again. The pins are press fit and MUST fit tight. If not they could work out of position and lock the steering. People have been killed because the steering locked and throew them off of the tractor as the tractor followed on top of them. Real serious business. I pressed mine in place and them put the smallest Mig dot that I could two places right where they sit flush on the outside of the actuator sleeve. I felt that was cheap insurance. The last thing you need to do is to set the actuator sleeve and cam spring tension using a dial indicator. I don't like to guess here. Once set, it is good for years. Now it could even be just a case of lower than needed flow rate. You can bump that up yourself. Search the archives for some comments on that, as I do not have a good photo with me on the road to post. If you boost the flow too far, you can get front wheel flutter as the system jinks from left side of the play gao back to the right side, and the oscillating is not something you need to have. Back the flow down until the flutter just stops. If it still hangs up, you have something from above out of whack. You mission is to get everything back into whack. The Power Steering manual covers the rehab of these units really well, and you need to read it several times before you go into them. Once you inderstand the function, it is really a simple unit. Frank
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