MTD Yard machines lawn tractor, how do I add oil to the gear box there is no filler hole?

Model # 13ai675h062





Serial # 1b131b30253





I have checked the manual and parts list for a filler hole but none is shown in the diagram or listed on the parts listMTD Yard machines lawn tractor, how do I add oil to the gear box there is no filler hole?
By golly , You are right , I can`t find anything either, must be a sealed unit. But on page 27 of the parts book it lists 15 oz of grease , so that would explain the lack of a fill hole . It looks like it is a one time thing. When the gear box dries up , you just get another lawn tractor.MTD Yard machines lawn tractor, how do I add oil to the gear box there is no filler hole?
The grease that goes into these transaxles is just regular chassis grease. The same stuff in your grease gun. It is put in when the transaxle is assembled and should never need servicing under normal homeowner use.