I recently purchased a Kubota L4610HST with 330 hours on it. Used the tractor for a month and everything was working great so I decided to purchase a new Kubota front end loader. I installed the loader and added almost 1 gallon of super UDT Kubota hydraulic oil to top of the system after running the loader long enough to fill the lines and cylinders. Used the tractor for about a hour one evening (both the loader and three point hitch) and everything worked fine. I was using the tracor tractor over the weekend to move dirt and the boom lift on the loader quit working correctly. It would only lift a few inches then stop and would only lower if the valve was put in the "float" position. The boom functions would work if the control valve handle was pulled/pushed at an angle which would enable a bucket function at the same time as a boom function. Example- It would lift the boom and curl the bucket at the same time; but would not lift only. It would quit lifting the boom as soon as the bucket had reached the end of its stroke. The bucket funtions continued to work fine. I removed the plastic cover on the valve thinking the linkage was messed up; but it was working correctly. Then I iunhooked the the hydraulic hose on the valve with the quick disconnects and then put them back on. Started the tractor and the front end loader was working correctly; noticed the 3 point hitch arms were all the way down and the selector lever was in the up position. The 3 point hitch arms will not raise!! I completly unhooked and the hydraulic hoses going to the loader control valve from the tracor and re-installed the factory plugs. Now the loader is not attached to the tractor hydraulic system. The 3 point hitch arms will still not raise. This is with no implement attached. You grab the lift arms and raise them by hand with no resistance. With the loader attached, there is plenty of hyd. pressure, the loader will pick the front of the tractor off the ground. Help greatly appreciated.