Both tractors in question have the control lever roll pined to the control shaft that goes thru the three point top cover and moves the valve linkage. On the right hand side, just inside of where your control lever in connected to your control shaft are two nuts, 13mm I believe, that adjusts the friction washers for the control shaft. If it is too tight, loosen the outer nut and back off the inner nut until lever moves to your liking. Re tighten outer jam nut.
If it is too loose, loosen out jam nut and tighten inner nut to your liking, then tighten outer lock nut.