What color scheme?

I have a 1996 JD755 MFWD HST. It has 667hrs showing on the meter but I don't think this is correct. The hrs. have not changed since I bought it last spring. The tach works but the hour meter does not. Is there something I can do to fix this outside of replacing the whole unit? I have run it about 10 hrs since I bought it. Everything seems to be ok with the tractor mechanically. It has 45psi oil pressure at idle and 53psi at PTO rpm after reaching operating temp. Doesn't smoke or use any oil that I have noticed. The engine feels pretty tight with reasonable power. The first day I used it, the temp got up pretty high. It smelled hot but did not boil over. My left foot got pretty warm though. I stopped the tractor and started checking it out and found a couple of issues. The prescreen and radiator were blocked rather badly with debris. The fan shroud was missing and there was no thermostat in it and the wire pulled from the temp sending unit. I guess the previous owner was having heating problems also. I pulled the radiator and had it cleaned and checked at the radiator shop, bought a new shroud and stat from the John Deere dealer and installed. Flushed cooling system and added new coolant. I also added guages for the Temp and oil pressure. Not a fan of idiot lights. I also changed engine oil and filter and Hydro oil and filters. the tractor temp has reached 165 degrees last summer under load. My left foot hasn't overheated yet. Sorry about the long post. Tim Herron(Bone)