I have a D-6 9U 49-52 model. The front blade goes up and down slowly any ideas where to look for the problem?
Well it hold position once you raise the blade?
Yes it will hold position,
If it holds position, rod packing, seal rings and check valves should be ok. Might be a problem with the pressure relief valve. There is a filter that should be checked otherwise your probably facing a worn out vane pump. How sloppy are the controls? I am assuming you have the Cat #46 hydraulic control unit.
Where would the filter be located?
ok, it raises and lowers slowly, what about the float position, has that been affected as well? Also did the problem arise suddenly, or do you have no previous history on the machine?
On the Cat #46 hydraulic control the filter is the cylindrical housing to your right when facing the front of the control tank.