3-Point Hitch Massey Ferguson 135 Position Control Not Working

[Smitty BaCall]

Well I repaired the position control problem, but I am not precisely sure about the exact cause. It could be one or more of three things (refer to photos below):
1) the eccentric (rear roller) had become displaced from the position control cam.
2) the front roller (position control) was frozen in place (i.e. sliding instead of rolling along the cam face).
3) the position control return spring was elongated (the last coil was stretched away from the other coils).
My thought is that the eccentric (rear roller) had become displaced from the position control cam. In the process of trying to understand the mechanism, I was moving the position control lever and "feeling" the cam with a screwdriver blade. I think I caused the rear roller to correctly re-engage with the position control cam tip. I replaced the spring, freed the front roller, adjusted the hydraulic linkage and re-assembled. The position control is now operating. At this point it seems to me that "Big" Dean Austin's fix (referenced in my original post) was to remove the top cover and re-position the rear roller on the position control cam. However, a broken return spring would also be a problem. I hope this may help someone in the future.
View attachment 322127
View attachment 322126

How did you adjust the hydraulic linkage. Book I have does not specified about hydraulic linkage adjustment

 

[klancf51]

I used AGCO publication 1448813M1. It is available at: MF-135 and MF-150 Tractor Service Manual.
I did not have access to the MFN tools. Instead, I used the figures in the manual to help me determine each tool's function(s) and fabricated ersatz tools/gauges. My recollection is that, as the hydraulic linkage came into adjustment, I could observe movement of the draft and position control levers transfer into smooth, corresponding motion in the hydraulic linkage, across the full range of the quadrant levers. In my case, this included the "CONSTANT PUMPING" (i.e. pressure control) portion of the position control quadrant.
Is my adjustment exact? Probably not. Does it operate the lift correctly? Yes - including plowing. Hope this helps.