8n 3pt will only go up and down..will not hold position

[Cptwayne]

I have an 8N tractor, with a nine man engine. When I got the tractor the three point would hardly lift. Open the side cover, and saw that the relief valve was bypassing replaced the relief valve and with the small lever in position moving the quadrant leveler up or down causes the 3.2 go full travel as soon as you moved to the up position it goes full up as soon as you moved to the down position because full down and there is no way to stop in between. Being a novice I didn't realize that it should have position hold so I bought a Zhang thing type attachment made by Redrock, but it didn't solve the problem I pulled the top cover and found that the cam follower was worn almost into, and the cam had a groove in it I replace the cam follower, and dress the top surface of the cam and attempted to set the two springs to the dimensions and the maintenance manual after reassembling it. I still have the same problem anybody got any ideas?