My three point had been working, but not perfectly. Had some bobbing but not real bad. My tactor has a front loader also and is working well. Slow but am told this vintage is slower. Just changed all the three reservoirs with the recommended hydraulic/transmission oils from Tractor Supply.....2 gals in trans.....2 gals in hydraulics....3 gals in diff. Dip stick on hydraulics shows past full but says something about arms being extended. (These amounts came from other 800 owners on this forum...via manual) Now my three point issue described. For the past week it was stuck in the up position...nothing would let it down. So, at this point I changed all the fluids. The first time I started the engine it dropped to the down position. I have a back blade on the tractor. Now, it will not lift. So, I took the back blade off. Tried to lift the arms and they gave me no resistence while I lifted it up to the up position. No pressure....zero. was hoping someone who has repaired or rebuilt their hydraulics for their three could suggestion what may be going on. If it is bad news let me down gently....lol.....thanks for reading this...hope you will be able to offer insight.