I purchased a Hyster S50XL forklift and did bunch of maintenance. Lots of water in hydraulic fuild, changed many oil seals on cylinders changed steering motor cause it was steering one way fast and hard the other way. Changed every filter washed out the hydraulic tank and put new AW32 S Super oil in it.
When the forklift lifts hard like lifting the end of a container the hydraulic makes an unneeded amount of noise "it seems as the pump", " a check valve", or "also sounds like if pump had gear drive, would click splines". It still lifts well. Would like to do pre maintenance before something badly goes wrong.