I have a Bob Cat 632 built in about 1982 when I first got it the previous owner used any hydrolic fluid that he could find, have have since changed to 10w40 motor oil that the book called for. in the past several years I have been having more and more trouble with hydrolic system over heating, it gets up to 220 degrees and quits working, the oil cooler is clear, the fins are clear and blower is working ok. In the past when I first got it when the bucket would get hungup it would cause the rear wheels to come off the ground it will not longer do that, also as it get hot is starts screaming like a banchee I have change the brass filteer several times also the Hydro. filter. what is going on with this machine?? Can any one give me some help??