I have a Ferguson TO-35 and I’ve had the tractor for over 15 yrs. This last summer the 3 pt hitch began acting funny. When I raise the hitch, the lever and the hitch start to drop back down. As soon as the arms are up where you want them, you have to hold the round lever or it wont stay. The lift lever slowly moves forward if you don’t physically hold it. Can you tell me what is wrong?
One of the first things to check are the Quadrant friction washers. There are coil springs under the screws that put pressure on the washers to hold the levers in place. If the springs are weak, broken or rusty they will not put enough pressure on the discs and the levers will move from where they are set. I would check these washers and loosen up the screws so you can adjust them to put more pressure on the friction washers. The levers should work smoothly and easily but you should be able to feel the drag of the friction washers when you move the levers. If the screws are rusted, you may have to replace them.
There are a series of adjustments that can be made to the internal linkage that can be made without removing the top cover. Those were described in an article I did for Ferguson Furrows.