Noticed coolnick72 comment on milky trans/axel. fluid. This is a result of water getting into the case from sitting outside uncovered. I have an Iseki TL4000 that had the same problem likely due to the shift handle missing boot ( a vw bug boot fits). The fluid has an affinity for water and captures it in solution. Problem is that the water vapor is continusiouly rising to the upper regions and condensing. Eventually the rusty bearings start to fail.
I have started with the 4WD front bevel cases and found everything to be in excellent condition except the upper countershaft bearing. This bearing would fail soon and there goes the bevel gears. As these units reach their 20-30 old ranges this type of failure will be quite common. As bearings are easily obtainable and gears likely impossible an aggressive approach to preventive maintenance is highly recommended. I plan on separating the cases this winter and checking the internals. Does anyone know if brakes are available for the TL4000?
As for the fluid, several changes are required to purge the water, as its not possible to drain it all at once. Boiling the fluid will expel the water but is likely more trouble and dangerous than it's worth. As for the drains, there are typically 2 drain plugs, the foreword plug is the clutch area and should be dry. Fluid in this area is seepage from the engine and transmission sections. The rear is for the main case and should hold 10-15 gallons for a 30-50 hp. class tractor.