I have a new 6-speed transaxle lawn tractor model 917.28807. I bought it new and have used it one season. I walked past the tractor in cold storage (minnesota) last week and there was grease or oil that had leaked from the axle onto the inside of the rear tire rim and down onto the floor. I want to know what is causing the leak. It is leaking around the washer on the inside. I don't think its coming from the wheel, but don't know. I don't think its coming from the transaxle shift which is somehwer above it, but I guess that's a possibility. Anyone know where this heavy black grease or oil is coming from?