HELP! John Deere Repair info needed, 3pt jumping

[jimgerken]

I posted this in John Deere Owning, but no info from there, maybe someone monitoring here has a repair manual and can look this up for me. I know there is a valve for synchronizing or equalizing or something like that, on the rockshaft housing somewhere. We used to do something similar with farm tractors now and then. I can't find this adjustment. The following may help to explain it also:
My JD4100 has developed a problem, and I thought maybe one of you guys had seen these symptoms before. The 3 pt hitch moves up and down about one-half inch at the swivel balls, all by itself when the tractor is running. The cycle rate is about one jump per second. The only way to stop it is to drop it all the way to the bottom. It will do it anywhere else, all the way to the top. This started after using my new tree getter, although I did not feel I was abusing anything. Is there something which needs adjustment, hopefully? Any suggestions? Thanks!

 

[DFB]

Jim,

The sensitivity adjustment for the rockshaft control valve on the 4100 is found behind the green cover below the front of the seat.

The set screw is held in place with a locknut. Turning the screw clockwise tightens things up.

DFB

 

[normde2001]

On a Yanmar that would sound like a dirty hydraulic pickup screen. I assume a JD has a similar screen to clean when the fluid is changed.

 

[Anonymous Poster]

I called the dealer about adjusting the rockshaft valve nut, he said you really need to hook up a pressure tester to the valve, you can over adjust the thing and blow lines and fittings.

I'm bringing in my 4300 tractor to the dealer in for this same problem monday morning 6/2/03 (still under warranty), I'll let you know what they find. Hopefully its something simple like an adjustment.

John