Tractor Repair: Ford 800 Tractor 3 point, series tractor, valve pressure

Question
Hi Arnie, I recently purchased a 1955 Ford 800 series tractor. When the 3 point hitch is all the way up it will lower a inch or so and then jump back to the top. This happens every 1 to 2 seconds. I'm also not getting any draft movement when plowing. I believe that this problem is something in the rockshaft housing that sits on top of the differential. My question is would a leaking o-ring or something similar in the rockshaft cause the tractor to not lift as much weight as it should? With a 3 point lifting arm on the tractor that sticks back about 5 feet or so the tractor won't pickup a weight of 200 lbs. If I repair the rockshaft assembly, is there an adjustment on it to set the lifting capacity and what should it be set to if so?

Thanks

Answer
Hello,


  The seal on the lift piston could be leaking which would cause the hitch to drop and go back up every couple of seconds.  It could also cause it to not lift much weight.  There could also be a problem in the hitch control valve.  I have no repair manual for it so I don't know what the hydraulic relief valve pressure spec is.  That would be the only adjustment that would change the lift capacity.