I have a B6100 with a tiller attached. I was using it recently and the hitch would no longer lift the tiller. I think that it has been slowly acting up as the tiller slowly was sinking down from the highest position. Sometimes when nothing is attached to the hitch and the control lever is not touched, the hitch arms would drop down on their own and the pump(?) would squeal until I moved the lever to the middle position. That would then stop it from squealing but it would do it all over again. Is something making the fluid leak by a pump or valve? There is no other hydraulic connections on the tractor, like for a loader. What should I look for to repair this issue?