I am trying to change the oil in the Hydro Gear ZT3400 transaxle. I understand to take off the filter and the drain plug. But, what the manual shows as a plug is the fitting/hose for the overflow tanks. Is this fitting what I remove? Also, it says to refill the oil through that plug. How do I do this since it is coming out of the side of the transaxle, not the top? Would it be possible to fill the overflow tanks and allow it to drain in?