My MTD 1024 24" says to grease the auger shafts if there are fittings, but there are no fittings. I have one zerk on the gearbox itself. Should I fill this with grease and how much? Any specific grease needed? My manual says nothing about a fitting on the gearbox itself. Would this have been greased at the factory before sending out? The zerk is in the gearbox in the middle.