Since no body else is answering, I'll give it a shot.
You might get better info by posting in the chinese tractor forum.
I've never seen a dongfeng, but I do have a Kama TS254. The Kama and all of the other chinese tractors that I have seen use a self contained 3pt hitch lift box with an internal valve and cylinder. There is ussually a knob that controls the drop rate of the 3pt hitch, and a bolt on the side of the lift box that diverts the fluid flow from the lift box to a remote. If your tractor has these that is where I would start. Either one too tight will cause the 3pt to stop working.
On my Kama I had a problem with the 3pt not working. My problem was caused by an O-ring blowing out in the control valve. I found the problem by taking the cover off of the lift box, and starting the tractor. No matter where I positioned the 3pt lever, oil was running out of the control valve. It was a fairly easy repair, once I found the problem.
Stan
