after doing a lot of research on the Peerless Hydrostatic 2000-002A or B you can change the oil by removing the pump from the transaxle then clean the unit before removing the vent tube and gromet located on the top of the unit, flip it over and allow the oil to drain. once the oil has drained replace it with about 2 quarts of Mobil 424 hydraulic oil, basically synthetic trans fluid.
insert a metal ruler into the expansion tank opening until it stops at about 5 5/8 inches. when full the measured amount should be between 3 5/8 and 4 3/8 inched. you might need to use a power drill to spin the input shaft up to speed to fill all the passages and get the air out. make sure you spin the shaft in the right direction for your unit, spinning in the wrong direction could cause failures.
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